I generally like PvP servers better because the player base is 'better at the game' in general. From the start of leveling in contested zones like Stranglethorn Vale you have to keep your camera on a swivel. If you don't, you're likely to get jumped over and over and over. This, in turn, forces a person to get better at being aware of their surroundings. On PvE servers you don't have to keep looking over your shoulder and you become accustomed to just staying 'tunnel visioned' at the single mob you're killing for that quest drop because there is no danger around you, no one to gank you.

I believe this directly relates to end game raiding. People who are more aware of their surroundings can generally get out of the 'fire' quicker and know WTF is going on during a fight. I back my statement up with WoWProgress [US] and WoWProgress [EU]. Look at the top 25 realms [or 50] of both regions...which server type are there more of?

So this is a main reason I deal with being ganked and what not during leveling, because when it comes time to find good players, without their heads in their asses, more of them can be found on PvP servers. This probably doesn't mean much to boxers since we are able to do our own thing for the most part, but I like raiding end game content solo on my main.