I was running with AOSP Strawberry Jelly Bean for a while and it started to be really slow and unresponsive so I tried AOSP SlimBean Build 5.
Didn't suit because I had random reboot even the UI was smooth enough... By the way, if your smart-phone is recent enough, I would recommend this one because it's highly customizable.

I finally ended up using the latest RC of CyanogenMod 10 (including Android 4.2) which seems to work perfectly and seems stable on my old Google Nexus S (codename crespo).

I used to use Titanium Backup to backup and restore my