Filen and MEGA are your best bets. Both are FOSS and use E2EE when storing data.
Filen, you can get 50 GB free, but MEGA, only 20 GB.
I chose MEGA because it has more users, larger company, and more employees. Filen is great but only has three employees as of now. MEGA has been around since 2013 but Filen is under five years old.
I want to wait for Filen to mature as a company and gain stability before entrusting them with my life’s photos.
Filen’s Android app is unpolished and has some bugs, which makes sense given how new it is. That’s why I’m using MEGA right now, as I’m waiting for Filen to become polished and bug free.
Both are excellent options, right now I’d pick MEGA, but maybe I’d switch to Filen a little later in future.