As always, i must say that there is no "best" thread. Performance and Battery life will vary for every user, given the combination of unique screen brightness, the applications used and desired settings. Most ROMs can be tweaked for performance and battery life; your best best will be to search the threads and find the ones that look interesting to you, and do some reading on them. .
HTC Blue Angel (retired)
HTC x7501 (retired)
HTC Incredible, w/ AOKP (GPS use)
HTC Rezound (backup phone)
Samsung Galaxy S4 w/ GPE 4.4.2
B&N Nook Color, w/ CM10
HP Touchpad w/ CM10
Google Nexus 7 w/ Stock Rom (STOLEN....
Google Nexus 7 (2013) w/ Stock Rom & Glitch Kernel
If you have any problems or questions, do not hesitate to ask. I don't bite!