I use a Yuasa OEM battery.....it's heavy but I'm not weight conscious.
Sometimes old and trusted is the way to go...
Others have used LiPo batteries with great success though....I personally would have to order one on line as there is nowhere around here that stocks them....and I don't like ordering something like this on line due to if there is any issue with it, having to ship it back is a pain in the rear.
Conversations regarding batteries around here rates up there with tires, oil, chains, etc, etc.....you'll get 100 replies with 90 different opinions.