I used to use SwiftKey, but Microsoft acquired and ruined it years ago. It worked really well. Since then the only one that worked for me is Gboard.

I've had this installed for a while but found the swiping too inaccurate. I'm trying it again now and I reckon it's as good as Gboard now. I've written this comment using it. Nice!

Edit: I've noticed that, like Gboard, it's still hard to type words like "fuck" or even "tits" etc. Are these words just missing from the dictionary? It's always felt like I'm not allowed to type them because I'm not a big boy. I don't type those particular words much, as it happens, but other missing words is annoying.