It seems to me that being that Google controls the entire operating system anyway, just avoiding the Google Keyboard wouldn't really do much to prevent them from snooping on your private data if they are so inclined. But doing so would basically mean that every developer involved in the android operating system was knowingly adding secret malware. It seems more likely that Google is behind faking the moon landings.
Incidentally, you didn't specify if the keyboard you are using is one of your own creation or something sourced elsewhere, but either way I would be more concerned that the alternative keyboard you are using would be MORE susceptible to attack from NON-Google third parties than the Google keyboard itself.