After Sync released I tried even more other Lemmy clients because of all the other recommendations in the Sync discussion threads, and there are definitely a lot of great Lemmy apps.
But as an old Sync (for Reddit) user myself I also get the feeling of familiarity using the Sync Lemmy app, with the customizability to even adjust what each "step" of the swiping gestures does, while using other Lemmy apps I mostly feel like I'm locked to "getting used to the app". So I understand why some people are so happy to use Sync again.
That being said I do agree that it feels expensive to pay even for ad-less, and people may not like that the free version has ads. I will probably pay just for ad-less (not Ultra) once I have figured out if I like any of the other Lemmy apps better (or not.)
I tried Infinity too, while I miss swiping to upvote and reply to comments, the swipe to move between previous/next posts was interesting, so I'll have to test it more to see if I like it!
Ah, found it now, thanks! I guess because swiping anywhere by default just went to the next post, I didn't expect it to have an option for swiping the comments too.