I've watched both of them. Both had good and somewhat different things to offer. If you have no competition experience I would say Pit Bulls. If you are looking to refine some skills and already know the basics of competition, I would say Kosmos. Like Jason said, Kosmos had some techniques and flavors that I hadn't seen before, and I've really come to like some of his products. Recently I think Pit Bulls had his class on sale for $150, which is a steal.
As I was just starting in competition bbq when I ordered these both offered me really good things. Pit Bulls provides a lot of written materials, like spread sheets with times and temperatures, which is a really good start. Kosmos showed me some trimming techniques and box building tricks that have proven valuable.
Both guys are really good at answering emails/questions. Best case scenario, if you can pull it off, buy a used Kosmos from a brethren member in the sales section of this forum, and try to catch Pit Bulls on one of their sales. If you follow him on facebook, I think they post them often.