I've used lots of batteries for my paintball playing - many different brands and types. I've used rechargeables and disposables, brand name and no-name dollar store varieties. I've tried bulk purchases, individual purchases and everything in between. Now, when I go to the store, I always pay attention to sales on 9-volt batteries (which are surprisingly expensive) and I've started buying Double A batteries in bricks of 50. I guess it's just indicative of what it takes to play the sport. Unless I completely eliminate all my battery-operated gear from my arsenal, I guess I'll continue to support the battery manufacturers.
Overall, I must admit that I haven't found a huge difference in performance of the batteries I've purchased. While the super cheap ones don't last, most other brands seem to do about the same. I no longer use rechargeable because they haven't lasted quite as well for me as disposables, but other people have found them to be pretty reliable. No matter what you purchase, I've found that the biggest key to batteries is just having some extra ones lying around because you're going to run out.
