Well, I suppose this question has been answered pretty well except for a couple of fine points that have been mostly missed but no worries really because most of the larger points speak loudly enough as it is. Clearly though, I believe that anything less than a stock Tippman 98 is a waste of time, and anything more than a stock T98 with a good barrel and double trigger and maybe drop forward and nitro that is short of a Cocker is a waste of money. It simply goes from Tippman with essential performance parts (air, Revo, drop forward, double trigger, and barrel....and if you REALLY WANT TO ROCK, the reactive trigger) to stock Cocker then beyond. No Spyders, Flatlines, (and in my opinion stock Mags) etc. can be rationally justified in expense.
Why a Tippman is not a Cocker and not an Angel that hasn't been mentioned already:
1. Too high firing pressure. Yes, there is a divided camp on whether low pressure is totally an absolute advantage, but basically there exists no solid arguement against 350 to 250 being nearly always better than 800, 800 being the operating pressure of most blowback co2 guns, and 350-250 and below being the operating pressure of Cockers and electros. "Why?" is the question always asked. Though many other answers are nit picky, an indisputable benefit is that it's gentler on paint, meaning that you're more able to shoot delicate paint that breaks better, and breaks are what count. That is a solid fact.
2. External moving parts. Tippmans are tough, very tough markers indeed, but they do have an open area other than the barrel, and although they can handle dirt and other nasty crap in them better than most any other, dirt and other crud makes anything mechanical stop working rather quickly. Angels, Shockers, Bushies, and with the exception of windowed bodies and the tiny gaps between the bolt and cocking rod in the back in Cockers, are all sealed boxes that do not invite dirt into their working mechanisms. Sure, they have a lot of other issues, but dirt is not a major worry and the other things can be preemptively treated and thus make those guns very reliable indeed.