I made this design from Matthias Wandel a few years back, and it has served me well. I had a big piece of laminated MDF that someone left in the garage after we bought our house -- perfect for the top. I do with that I had something heavier for when I need to whack a chisel or do some ripping with a handsaw, though.
I have a mix of a roubo and an anarchist bench. I use the leg vise way more than I ever thought I would, and bench dogs are king for me. The tail vise gets a fair amount of use too. I didn't add a sliding deadman to mine, and I regret it (I have some dog holes in the right leg, but want some closer for smaller stuff). Its my first bench, so I've learned a bit making it as well as using it, so maybe in 5 years I'll make an updated one (which should go easier since I'd have a bench to build the bench on lol)
Do you primarily use hand tools or power tools? Also, are you looking for a primary work bench, or an assembly bench?
Hand tool benches, you want them to be really heavy and sturdy since they get loaded in shear a lot by things like planing and sawing. For a hand tool bench, you basically need to decide what you have to work with, and what your work style is like. I like go be able to just clamp stuff to my bench top, so a Nicholson bench is a little annoying for me. Also, think about the space you have available, and whether you are right or left handed. For handtool work, I would prefer a face vice and a tail vice, with plenty of dog holes.
For power tools, the name of the game is modularity and mobility. Everything should be the same height and on wheels so you can move stuff around to act as infeed/outfeed tables. They don't need to be as heavy or sturdy, so you can use some space under the bench for more efficient storage. It's also nice to have a few ways to clamp other tools down.