I think of the paints I've used, Marballizer is still my favourite, though I've seen a bad batch or two. But when they're good - they're good.
Here in Canada there's also Inka, whose Silver-grade paintballs are a really good value. They're very consistent in shape, fairly brittle, and significantly cheaper than the competition. They make Copper, Silver, Gold, and Jungle (like Camotac, but with an available blood-red fill). They also do Bioballs, which I've heard aren't very good.