I have always used SwiftKey and Android. This year I switched to Apple because Android was being bloated by Samsung etc. I'm shocked by how horrible Apple keypad is. I also feel like the touch sensitivity of iphone is worse than Samsung phones.
I installed SwiftKey on iPhone too but even it seems sluggish.
Long a swift key fan but ever since it got sold to MS, it has gone downhill. I have it on my iphone and I think the development on that has stopped. My favorite keyboard is just unusable.
I went to apple keyboard and had to disable autocorrect because it would uncorrect it to the wrong word until five words down and decides which word makes more sense.
I went the other way this year, from an iPhone to a Z Flip 7. It's generally been a pretty good experience - the bloat on Samsung devices seems significantly less bad than it used to be 7 or 8 years ago.
I've stuck with Samsung's keyboard and it has mostly been fine, though it's less aggressive about adding punctuation for contractions etc.
+1 on GBoard - every time an app has that weird bug where it selects the native ios keyboard instead of GBoard it doesn't take long for me to notice, it's crazy how bad the Apple iOS keyboard is by comparison.
I installed SwiftKey on iPhone too but even it seems sluggish.