Honestly? Ramen. There are way too many ingredients that all needs to be cooked differently, and even the broth itself is a nightmare amount of effort for what you get at the end.
Crepes? Jesus, they're one of the easiest things you can cook.
Anyway, to answer your question: croissants! I've made them from scratch before and it definitely wasn't worth it. Took half a day and weren't a patch on the real thing
Baklava. I love it. When my aunts make it it's always amazing. But holy crap if it isn't the most tedious, fiddly, obnoxious stuff to make. And that's if you're not also making your own phyllo dough... all like six miles of it that goes in a batch one vapor thin layer at a time.
Chinese food. The common fast food type here in the US. Yeah, I can spend a bunch of time, work, and money to make orange chicken, boneless spare ribs, crab rangoon, teriyaki, coconut shrimp, and pork fried rice. Or, I can go 5 minutes up the street, and pay my favorite restaurant $20 for a big plate with all of that, with absolutely no work on my part, and it all tastes way better.
Pumpkin pie filling. The real stuff takes forever and it’s stringy. It also doesn’t taste quite the same. Libby does it so well it’s not worth making your own.
My wife says pie dough. Pillsbury’s is almost as good and a lot less effort. I prefer pie dough with a ton more butter but she doesn’t.
Croissants. Only really good when an independent coffee shop makes someone come in at 4am to start making them. Even the industrial ones at the big chains or supermarkets are pretty meh and it's way too complex and time consuming to do myself but made right they are one of the best foods.
Pho. I have a killer recipe for the instant pot but it basically works out to the same price as just buying it from our local takeout. And they're Vietnamese.
Macaroons. I have made them from scratch. I can appreciate the sophisticated sublime expression of culinary caution it takes to split egg white, whip them until hard peaks, and then gently and precisely fold in the other ingredients to get the flavor you are after... But holy hell is it tedious with lots of potential for failure most of the way.
Alternatively, making cinnamon rolls from scratch. Not because it's hard, just because it takes too long. I believe the recipe I was using allowed the dough to rise three separate times. Simple enough to make, but planning ahead for them to be breakfast is a 16:00 the previous day commitment.
Now I dont "love" them as a standalone but I do a few really nice loaded versions for catering family events. I tried to "elevate" my dishes by making my own and while I could and they were a little better it took half a day and a shitload of mess.
That being said, spaghetti sauce. Yeah, home made is better, but "doctoring" a jarred sauce gets 95% as good without hours of work. You can't fix the canned shit, but I've not found a jarred sauce that I can't tweak with fresh herbs and some quickly sweated aromatics and end up with something that people love. It also satisfies my picky ass. Now, I will say that fucking ragu is pretty shit overall, and doctoring it only goes so far. But it is still good enough that making sauce from scratch ain't happening.
Edit:
There seems to be a lot of range in spaghetti sauce recipes. It's also important to note that I'm not talking about marinara.
So, the real time involved is split between prep and simmering.
Here's how we do it. Remember this is an american talking here, so don't redirect expect something traditionally Italian. And I'm a southerner that's mostly german and Scots-Irish, so don't expect any new York style stuff lol.
You take your tomatoes, skin them however you prefer. I use a quick dip in boiling water, aka blanching.
You give those peeled tomatoes a rough chop into nice size chunks. Now, the kind of tomato matters for that because something like a roma e isn't gong to need as many chops as a beefsteak. You'd usually be using something like a roma anyway, but if your neighbor drops off a giant bucket of tomatoes, you can only use what you got, you know?
You chop up an onion, maybe two. You mince some garlic, maybe half a bulb if you really like garlic. I love garlic, so I go heavy.
Now, that's your usual start. Most people in my family don't add anything else in the way of veggies. Me? I like to char a couple of red or yellow bell peppers, skin them, and get them in there too. If I'm feeling frisky, I might have zucchini, eggplant, or whatever else cut up and ready to add at the appropriate time too, but that's optional.
You get the onions sweating. While they're starting, you feet your herbs together. Idgaf about fresh vs dried, each has benefits for flavor, you do what you prefer. I do oregano, basil, marjoram, a little thyme, and that's it. I'm simple.
A little black pepper, a little salt (you really don't need much, maybe a teaspoon for a big batch; salt your damn pasta water instead) to taste.
Once the onions are almost ready, I add the peppers since the quick char and steam to peel them tends to get them halfway cooked anyway.
This is around a half hour of work for most people. For me, it's closer to an hour. Yay disability!
Then you add your tomatoes, herbs, and any optional veggies. Bring to boil, reduce to simmer.
After that, it's patience. You're making sure any veggies added are tender, and after that it's cooking things down and letting the flavors develop. And, I promise you, anything under a half hour of simmering isn't going to taste right, and will be super runny. You'll usually have what amounts to chunky tomato water until close to the hour mark. For a big pot (my biggest is 6 quarts, and it starts damn near full when I do it) an hour and a half is bare minimum for the right thickness.
Now, if you're going to jar that up, you're done except for that part, which isn't involved in what I originally said.
If you're going to add meat, you'll want to start browning it off about a half hour ahead of when the thickness will be right. You add the cooked meat in and let it simmer for 15 minutes at minimum. Do yourself a favor and deglaze the pan used with a nice, semisweet red wine, add that to the pot and go at least a half hour after adding it.
Now, exactly how long it needs to simmer is variable because you're dealing with tomatoes, and the water content varies between varieties, time of year, weather conditions, etc. But I've never had a full sized batch take less than an hour and a half counting from the initial bring-to-boil stage.
I dunno, maybe there's time savers I've never thought of. Maybe the folks saying it's a half hour are doing a different version of "from scratch", or whatever. But that's how we do it, and it's pretty much what the typical recipes I've seen online do (I went and checked because I wondered if I was crazy lol), plus or minus some details that don't really change simmer time.
I've had some batches need a full two hours of simmering. And, yeah, you don't have to stand over the pot the whole time, but chances are you'll still be in the kitchen cleaning, keeping an eye on things stirring occasionally, adding any herbs or spices to adjust taste as it goes, etc. So it isn't like you can just pop down to the local pub (or equivalent in your location) and go by time alone. You'll still be in the general vicinity, with the added heat and humidity from cooking.
But that's why I rarely go from scratch. I can pick up a jar of whatever, add some herbs, extra garlic and/or onions, brown any meat and then the deglaze and be done in under an hour from start to finish, including prep. The taste isn't the same, nor is the texture, but it's still yummy.
French Fries. For those who don't know, when starting with a potato, you have to fry them twice. Once at a low temp to cook through, then again at a high temp to crisp up and brown. The frozen fries at the grocery have already had the first fry.
The double frying is just too much effort when the frozen stuff is just as good, even in an air fryer. So long as they're hot, the drive thru can compete with anything you make at home.
I used to feel the same way about egg rolls, but the product you get from scratch is superior to frozen or even take out.
Almost anything that involves phyllo dough. Banitsa is worth occasionally doing homemade only because you can't really find it anywhere, but anything else is just not worth it.
A lot of French cuisine. Not talking about laminated dough here which I've done many times. More so the complete modern French meal involving multiple reductions and real demiglace and all the techniques that seem to require a full restaurant process. It's the one style of food I will go to a restaurant and happily pay for once in a while, I understand why it's expensive to make and respect the skill it takes.
The other style I food I do this with is the very opposite, shitty fast food I can't make at home.
Halal Chicken and Lamb over rice. I've made my own at home before and after all the effort that goes into making the sauces, the meats, the rice, and veggies, I somehow end up with a dish that cost at least twice what street carts sell, at 5 times the length to make it and isn't as good. I wouldn't make it at home unless I lived somewhere where that was the only way I could get it
There's a lot, most of which I make anyway for sake of cost/volume ratios, but in no particular order...
Tomato paste (love to use, can't be arsed to make my own), sriracha (like it but don't use enough for the amount I make), waffles (don't crave them nearly as much as I used to), scotch eggs (love 'em, hate making 'em), pickled asparagus (which really sucks because they're so good), lotus root chips (maybe if I had a fry daddy, air fried just doesn't do it), chicarrones (lots off local places make 'em fresh and cheap), horchata (same), meat pies (there's a local Brit shop that sells 'em), falafel (lots of local vendors), jalebi (way too much work)...
You do you, but those are not difficult to make IMHO. I make a ton of batter and keep it in a squeeze bottle so I can easily make my kid pancakes in the morning
For me it's macarons and most baked goods
I still make lasagna from scratch but that's because I have to use gluten free pasta. All the pre made versions are awful
Stuffed vine leaves. I made them once for a gathering I had and they took me about 3 hours in all. Everyone loved them but for the time they took me, and how much of a pain in the arse they were to make, it wasn't worth it. The ready made ones in tins are just fine.
Never made any before but broth doesn't seem worth it unless you make a big batch, even then I don't have the room for a big ass pot or a gallon of broth in my fridge/freezer.
Wide rice noodles. If you've ever tried to make pad kee mao (drunken noodle) with dried rice noodles you know it's essentially not even worth it. The noodles are too important to the dish and the dried ones curl up and are just awful. My wife and I eventually figured out how to make fresh wide rice noodles and while it's very simple to do so (rice flour slurry into a cake pan, steam it) it's very laborious and time intensive. I'll do some laborious stuff (bake my own bread, homemade yogurt and soft cheese, pasta and red sauce etc) but damn if one of my favorite foods isn't too much work for all but special occasions.
Thank god we found a place a mile away that sells fresh noodles. Now we can have it whenever we want.
Churros! The recipe, by itself, is kinda easy. But, to do a really good one, it needs to be done in a perfect way. A very, very tiny error, while not ruining the recipe, will made a "maybe tasty, but not that good" one! I would rather to buy in a street food place and eat if I want to. I live in Brazil, so it is kinda easy to find one!
Spanikopita - or anything with layered phyllo dough
Char Siu Bao - so delicious, so fluffy, but the Chinese yeast dough is much more difficult to perfect the texture of than regular dough
Ramen. There are a lot of ways to do the broth faster, but nothing beats the real thing that needs to be boiled over several hours; and I don’t have the time to do that. I make a lot of other japanese dishes myself but ramen will always be eaten at a restaurant.
Gaufre de liège. I made a very authentic version once, involving making a brioche type dough over a few days, giving time to rise and for the perle sugar to rest. Best waffles I've ever had, but so much trouble.
I haven't found them outside Central Europe and miss them so much I have been thinking about making that dough again...