Google drive is free and surely pretty well backed up, but requires hoping a service with no customer support process at all just never decides to kill your account, and probably they scan your drive contents just like they do your email, or will some day if not yet.

Onedrive requires creating and using a Microsoft account and who knows how usable it even is from linux (can it do a synced folder on linux or just the browser interdace?).

Other services like Mega or idk what maybe don't have a folder sync feature or something, but are hosted in another country and possibly better protected against invalid take downs or spying.

So nextcloud costs a little more or is a little more work to set up. Yes and in trade for that there are other differences like you are the one in ultimate control of your stuff.

You may not prefer that particular set of trade-offs, but fundamentally, so what? There is always a trade off of some sort including with dropbox.