Gboard with every connection blocked through Rethink Firewall except for "media.tenor.com" and "tenor.googleapis.com" (because GIFs are cool).
I will never really know whether it really protects my privacy or if Google has other means to exfiltrate my data, but from Rethink logs it seems to be working. Unfortunately I have never found any keyboard as good as Gboard, so I would say this a risk I am personally willing to take for the convenience of a great keyboard. What would you say?