I've have good experience with MEGA, they were offering 50GB free when I signed up, I think they're offering 20GB on their free tier now. Your files are stored on disk locally while also avaliable on the cloud via their website and mobile apps.

I sync my entire home directory to a google drive i bought the maximum size plan and only use about 5% of it. All my passwords are in plaintext .csv files and sent to the backup along with scans of all my important documents and financial info. The google password is 1234 and i turned off 2FA for convenience. :)

Hetzner Storage Box.

I've been using mega synced folders for most stuff. Works fine.

I've been using Filen, seems to work pretty well, it's got a Linux version of the desktop sync client (comes as an AppImage IIRC) and I dunno if they're still doing it but they used to have a good price on lifetime plans that were ~100GB that you could stack, so I got a good amount of storage without having to pay a monthly fee.

Proton Drive is working well for me so far.

I use iCloud and Sia.