Not sure why you would want GB. current stock ICS FI27 has very good battery life. Also CM10 Jelly Bean Beta 2, has very good battery life. Both of those roms are stable with minor bugs.
I personally switched over to CM10 Beta 2 which is very stable and has a good battery life. There are many roms that can satisfy everyone's taste, but I prefer to stick to the larger more well known development groups (Cyangenmod)