I’ve switched to Gboard on Android back in the days, when it was the only one with proper multilingual features, and been using it ever since.
I’ve experienced the opposite: I actually found it rather more helpful than not, despite the occasional errors like you mentioned. But nowadays it’s quite rare that it “mispredicts” a word. And what I’ve found extremely helpful is, that nowadays it doesn’t only correct individual words, but it picks up other grammatical errors as well in the sentence. So it’s working for me.
The amount of people not knowing what a “web app” is, is seriously concerning.
Anyway, I tried “old” and Alexandrite, but I just ended up sticking with the default. I find “old” ugly, and on Alexandrite, I couldn’t find my saved posts. Maybe it has been fixed since, but the default one works for me best.