There's plenty of decent brands out there: EAM, GensAce, Sunpadow, Cayote, EZPower, Exalt, DXF, Intellect, etc

I think that the best approach is honestly just to look at what the fast guys at your club are running and what your local hobby shops can reliably stock. Batteries are a pain to source (depending on which part of the world you're in), and having something you can easily replace or match is usually worth more than chasing the perfect spec on paper.

I personally run Mach-1 batteries because it's local to me here in Australia and I prefer to support a local company. They run great and I've never felt that my batteries were a limiting factor in my racing.