I'm using Mega (20GB free) and Internxt (1TB lifetime plan). I have not done any particular research, nor have I read their privacy policies. I'm in the early stages of planning my transition to self-hosting, checking out hardware prices and drawing logic drafts of the interconnectivity (LAN, WAN, me, groups, others) that I want to be able to achieve.
Internxt forces you to use their app on your phone unless you enable viewing the desktop version of the website. Even then, they have made it so that uploads and downloads eat all your RAM, crashing the browser before larger files can finish processing. A workaround is to use their app or .appimage if you're on Linux.
I haven't used Mega long enough to be able to say anything about it yet.