Mlem. There isn't really a main reason. I like it because:
It's native SwiftUI, so it feels super snappy and "Apple-y" the same way Apollo used to
It's FOSS (though that's sort of table stakes around here)
The widget customizer thingy on the beta build is absolutely fantastic
It's not ugly. There are a bunch of apps that just sorta aped the Apollo UI without any of the attention to detail
I have a ton of faith in the stability of the dev team. There was a bunch of drama early in its development and I was pretty sure the project was going to die, but it didn't and it's been (as far as I can tell) smooth ever since
My only gripes are that the scrolling is still sometimes funky on the beta build and development isn't the fastest, but once all the apps are in their fully-built stable state I think Mlem is absolutely going to stand out among the crowd.
Awesome. Is keyword filtering available? Didn't see a feature list on github, I'll give it a try anyway but that kind of filtering is what I'm really looking for.