Neither game is "better", as people said they're just too different. Just watch a few vids of each game to see which of the two's gameplay appeals to you most. Both games are full of character, stunning landscapes, and each has their own individual brand of humour, but both of them in very different ways. Gameplay-wise I like the feel of Conan more, WoW just feels less immediate (might be the autoattacking, or the lack of collision-detection). Conan is unfinished though, it seriously needs more time to mature. This isn't just about quests that you can't complete cause of some bug, or the occasional mob that doesn't fight back, or the occasional crash or bad framerates in some areas: I'm talking about some quests that you can just tell were hurriedly thrown in at the last minute, some zones that are completely empty and devoid of life, presumably pending some update, and an underlying rules mechanic that needs a serious amount of fine-tuning before it can feel fair and balanced (and that's just after they fix the various skills that aren't working).
The game's development manager was recently quoted in an interview as saying that if WoW is a McDonald's burger, Conan is a good expensive steak. Now, I'm a huge fan of this game game, but even I thought that he was pretty much asking for someone to come back to him and say "you obviously like your steaks rare to the point of being undercooked then!"
That being said, I do think it's an apt comparison, as it's a game that's a lot bloodier, a lot harder to chew, but, in my opinion, ultimately more rewarding than any other MMO onthe market atm. I don't even think you should concern yourself about the fact that it's unfinished, as they're working frantically to fix it. The first 20 levels of the game are polished to such a brilliant sheen that not only will you see your reflection in it, but your reflection will jab its fingers in your eyes and decapitate you with its axe, and they've been improvign the areas after that as well. I seem to be about 10-15 levels ahead of their polishing schedule unfortunately - if I were to stop playing for 2 weeks I'd no doubt come back to a much better game quest-wise!
Anyway, my opinion is that if it's open-world exploration that you like in an MMO, WoW wins hands down. If you want raiding and "phat lewt", WoW probably wins again (although I haven't seen too many of AoC's group instances yet, and there's every possibility that the high level ones will turn out to be amazing once I get to 80) simply because AoC is not an item-centred game, so you won't get awesome bits of gear dropping from bosses to make you feel like you've really accomplished something in clearing that dungeon. If it's community I can't comment as I haven't experienced much of WoW's, but I'm on an RP-PvP server in Conan and people are surprisingly mature and friendly - even the player-killing is done in a spirit of good will
If, however, it's pvp action you want, I think in the long term AoC will be a better investment even though a lot of the endgame PvP either isn't implemented or is buggier than a beehive on Windows 95 right now. I mean, just look:
this is some random guilds fighting each other in one of the high-level areas -
http://files.filefront.com/SUNDay+22062008avi/;10766788;/fileinfo.html
and this is possibly the most skilled melee player in the whole game giving a freaking masterclass in melee skills -
http://files.filefront.com/Mephs+Ragni+Entourage+lavi/;10700925;/fileinfo.html
I'm sure the wow players can provide some similar videos for you to look at, then you can decide which game's type of gameplay is more up your street.