I still feel the pinnacle was ~2011 Windows Phone. It was some kind of swipe-to-type, but maybe not Swype specifically? At any rate, it seemed to use "how humans actually talk" as a guideline, because it was do a great job of predicting what words I would actually mean to use in a row.
Modern keyboards are like, I know you just said "I want" but instead of predicting "to" I predict "rip". I mean the letters are close. And "I want rip" makes way more sense than "I want to." You're welcome!
Apple keyboard is shit. Swype (the one Microsoft bought) is better but still shit. Gboard is ok. But none of them are close to that windows phone keyboard. I still miss it.
Suggests words that make no sense, preferring rare words to much more widely used and obvious matching picks. Has the vocabulary of a poorly educated five year old idiot savant — fails to complete many words you use fifty times a day, but sometimes surprises you by suggesting something you'd hear a couple times per decade. Doesn't know other forms of the same word, forcing you to correct it manually over and over again, often failing to remember the word until you type it in four or five times.
Yes, I've downloaded all the dictionaries, tried it on many phones, and my friends are of the same opinion: it really is just bad.
This is a patent case where IA made a function worse instead of better, yet companies clinged to it for some reason.