Ask HN: What is your opinion on non-mainstream mobile OS options (e.g. /e/OS)?

Pretty much the title. Context: I have to change my phone, and I thought it is also an opportunity to think about what I would value in a phone OS (privacy and control) vs what I would need for convenience (app availability, seamless connectivity, etc.).

I am gathering opinions, and where else to ask this but here?

What is your experience/thinking on mobile OS options? Would you recommend any brands that use non-mainstream OS versions (eg Fairphone)?