Is any of them perfect? Of course not. They all have their unique quirks and UX style, but that’s imho what’s so great. There is choice, which is more than can be said for other platforms.
Why do you think people don't stay on Nostr long? The user experience sucks. We have a lot of choices but no real good ones for new users to see how cool Nostr is
Probably a mix of a lot of things, imho. Content, network size, tech hurdles and yeah: client UX. I don’t think there is THE client though. Users have different preferences, different flows they are used to etc.