I just downloaded infinity to give it a shot and I find the UI to be a little rougher around the edges. The most noticeable is the layout of posts on the feed - the icons dont look like they are consistent sizes and the lack of grouping compared to Sync (like having a box around both vote and vote count) makes it look more cluttered. I also think the default theme color (the intense blue color) kinda hurts my eyes because it’s too high contrast maybe, so changing that was the first thing I did- I think having a milder default would provide a better out of the box experience.

I have no major gripes about the base functionality, they’re both functional enough for me but the aesthetics of sync win for now. Also it seems like both sync and infinity don’t collapse the comment you pressed and only the replies, making it seemingly impossible to collapse top level comments which inconveniences how I read threads, by collapsing top level comments as I go down the thread - long top comments stay expanded so I have to scroll past a lot more.

Those are my first impressions based on never using either sync or infinity (be it lemmy or reddit) before like this week.

Edit: Just downloaded Connect too, looks very similar to Sync in level of polish so I think those will probably be my top 2