Default Hacker-friendliest Android phone

Hello.

I am thinking of replacing my Xperia Play with something fresher.
Is there any Android phone that is sold rooted? Probably not, so what's the closest to that?

I like having my phone rooted (mostly for firewall and permission management), but official OTA updates usually keep removing root, so I'll probably have to use an unofficial ROM. That's fine by me, as long as I don't have to keep flashing for every update. I think CM is my favorite.
What's the best phone-ROM combo to have both, the latest Android versions (with updating being as little of a hassle as possible), and root?

I hope I'm being coherent.