I'll add more apps to this list as they are released.
Since all these apps are being constantly updated, I'll also include the version number. Please don't let my post stop you from using any of these apps. My complaints will probably be fixed very, very soon.
Summit v0.1.22 (Day 1): The app is pretty neat since they added inboxes halfway through my day. The app feels pretty neat overall. It will be much better once they add profiles. I just wish they had an infinite scrolling feature. The community selection feels kinda wonky though.
Connect v1.0.73 (Day 2): This is probably the best app for Android right now; but I obviously can't tell since I haven't even tried half of them yet. Nothing feels missing from this app. It's great and has all the features I could want from a Lemmy client. The only issue I had was that some communities sometimes don't appear in the hamburger menu. I check up on my Stephen King community every few hours but I often have to search for it to find it. Overall an amazing app.
fennec v0.0.4 (Day 3): Overall a pretty neat app. It doesn't have too many formatting options; no button for adding pics to comments. The reversed voting buttons were kinda annoying and sometimes when a post had too many comments or votes, or when I was deep into a comment thread, it wouldn't show the upvote button. Also idk if it's just me being dumb but I can't figure out how to edit posts...
Thunder v0.2.1 11 (Day 4): It's a decent app. I don't really have much else to say about it. My only complaint is that you can't add images to comments and posts. If you don't really care about that it's a good choice for your main app.
Lemming 1.0.0-alpha05 (Day 5): It feels different from the others apps I've tried so far (probably just because of the unusual hamburger menu) but it's great. Profiles and inboxes are missing but i liked the UI colors quite a lot which made scrolling through it fun for me. Also, swiping to upvote requires a very small swipe on this app so I used it quite a lot whereas I literally never used it on the other apps. Pretty great and it's probably gonna be one of the best when inboxes and profiles are added.
I keep trying all of them but keep coming back to Jerboa. It uses it's screen space most efficiently (even with all the customisations of the others) and for me seems to work the best.
Edit: Connect is probably the next best one I've tried on Android (and potentially better functioning than Jerboa), but the font is too bold however small I make it.
Also connect doesn't seem to be open source, that is sad.