SLA 12v battery may do but are heavy. If you go down that route powersonic are a decent brand and low cost (although they are all very much the same). They come in various capacities, 9A 12v are amongst the popular ones. But the downside is the size and weight of them.

Alternately you can go for a 3S or 4S LiPo battery and some regulators. 3S max voltage is 12.6v (3 x 4.2v) but can drop to 11.4v (3 x 3.8v) when going flat (can go lower, I wouldn't recommend anything under 3.8 per cell). 4S is 4 cells so more than 12v (4 x 4.2v so 16.8v fully charged), it would need a 12v regulator if the accessories are dependant on 12v and nothing higher.

Personally I've become a fan of LiPo due to the low cost, high capacity, lightweight and small designs but there is something to be said for SLA too if you don't mind the size and weight.

@aameralis have you compared them to LiPo batteries though?

A 5Ah Powersonic SLA weighs 3.5Lbs and is 90x70x107mm A 5Ah hard cased 4s LiPo battery weighs 1.16Lbs and is 139x45x44mm

Define best :)

Thanks Guys. I'll step back from this developing debate. I think I have enough to go on.

Excellent advice as usual.

Daniel :P

No debate, each have their advantages and disadvantages, I'll just supply the facts and let you decide :D

SLA Safer No problems with under voltage

LiPo Lighter Smaller Ruined on under voltage