I've been using Boost. It has user tags, instance blocking which can even be extended to comments from blocked instances. Search is kinda eh, and sometimes gifs from less common sites won't load, but overall I'm happy with the experience.
Previously I used Connect. It was pretty good. Had similar features as Boost, but I found more issues loading content with Connect. Admittedly that was about a year ago so things may have improved, but I haven't gone back to check.
Sync has ads, unless you do a one time purchase, I don't think I paid for boost but I could be wrong, either way, I have no issue supporting developers. Just because something is paid doesn't mean it's inherently bad, if they're making a living making these apps and they are dedicated to making them better and better I have no issue contributing financially. They are the best two apps. It's a one time purchase, not a subscription. You can continuously support if you like but it's not mandatory. And yes they're closed source, which isn't ideal but I understand the want to protect their code if it's their livelihood and they've put so much effort into them.