What keyboard should I buy for my iPad?

I have an older iPad Pro 2nd Generation 10.5" and I'd like to purchase a wireless keyboard. I'd prefer not to spend lots of money like the ones in the Apple store. I searched the internet including Amazon but read many bad reviews and many of the keyboards were attached to a case which I already own. Can anyone suggest a keyboard they are happy with? I'd like a smaller keyboard if possible. I hope maybe next year to upgrade my iPad so I'd like the keyboard to be compatible with that one too. Much appreciated.

[Re-Titled by Moderator]