To all the people saying this game is better because it's free, if he doesn't mind paying, then it shouldn't factor into his decision. Also, it's pretty useless to poll this kind of question here since most of the people are pretty biased and shit their pants at the thought of playing another MMORPG (same thing for any other game forums...Watch, go to a guild wars forums and ask if GW or WoW is better). Back to the question, WoW is the much better game, better graphics, playability, actually has a storyline, etc. The only thing I think EL has better than WoW is the community, and to be honest, EL's community is starting to go to shit as well so that may not be for long. But as stated as before, EL is still in beta and it may get much better eventually, but for now, WoW is the much superior game. PLUS! Blizzard has yet to fail in any game yet, so this game is pretty much guaranteed to be active for a loooong time. Just my 2 cents (not worth as much due to inflation...)
[EDIT] Oh! Many people have different tastes in games, if you rely on everyone else to choose everything for you, you may regret it later, choose which one you think is more fun. Simple as that.