Proton.

Also, Collabora office looks really great too.

Proton drive is fine, their docs service is usable but could use improvement. Their secure and private file and docs sharing with other Proton users could be a great feature, if you need it.

EDIT: I just re-tried Proton docs and spreadsheets - much improved docs, and I think the spreadsheets are a new feature; looks OK but I am on mobile right now so minimal testing.

Proton, only as transition technology.