to me the most efficient rom is Sharp ROM for daily use. I root it and removed the bloatwares, and I got the most efficient ROM, be it touch smoothness, speed or battery backup. I use to get rare occasional restart, might be due to removal of many system applications.
pros : it is stock rom, so everything is working, no issues whatsoever.
cons : no oc custom kernel ( doesn't matter to me, normally I use to keep it underclocked) . can't tell about gaming experience with it.
PS : I installed 'Notification Toggle ' from market to get toggles, shortcut or direct applications from the notification bar. it is more than what we get in miui /cm7 notification bar. for 4-way boot I use 'power ' from one of FR 's miuis. I use GO launcher, contact and SMS and happy.