>>502111980pvp pro: wpvp is at its strongest in vanilla, feels like the intended way to play the game with the 2 faction system. if you really really like wpvp and ganking, there's no contest. fresh is also the best time for wpvp since nobody is level 60 yet and theres a much more even level distribution in the zones.
pvp con: if someone really doesn't want you to play the game, you don't get to play the game. you can't opt out of it no matter what, so if you just don't feel like fighting the other faction, too bad. really horrible to play a class or spec that isn't good in pvp, you're basically always a free HK if you're a healer solo.
pve pro: you never have to worry about getting ganked, can just do the stuff in the world that you want to do without someone getting in the way. you don't have to worry about things like not getting the darkmoon faire buff due to it being camped. you can also turn on pvp whenever you want on the off chance to bait someone into attacking you, or you run into another player who also actually wants to pvp
pve con: opposing faction feels redundant, everytime you see an opposing faction player it just feels kind of hollow that you can't really do anything with them. there's also less danger in the world which can make it feel a little more dull.