Main issue is if you will be racing under BRCA rules at any point. If you are, you will need a LIPO on the accredited list
http://www.brca.org/index.php?q=cont...-updates/14218
I like Orion and Vampire but all the premium brands are good from what I hear. Gens Ace are cheaper that the premium brands but I have not used them.
If you are not bothered by BRCA batteries then many recommend the Turnigy nanotech from Hobbyking as they are good and very cheap.