That's a rather unrealistic comparison to ask for, at this stage.
I've been playing wow for 2.5 years and only just started to get sick of it because of the wotlk raiding set-up which I consider to be highly tedious (same content over and over whether it be from 10 mans, 25 mans, easy, hard or heroic modes), but I've yet to find an MMORPG that has me hooked for the same amount of time.
From what I can see of Aion at this early stage, the graphics (one can spend hours on just the character customization screen) and some of the features are great (the inbuilt quest helper for instance is very good and gaining XP whilst levelling professions and gathering items is also a good addition), but it does lack in other areas, as you'd expect from such a new game (i.e. the non customisable UI is a pain and there are no addons available to help with this, as yet). I've also not experienced any instance raids yet so can't compare like for like with WoW. On a side note, I am told that Aion is in the main a pvp game, which, if true, will seriously affect whether I play it or not, as I detest pvp with a vengeance; if not, I'll continue until it bores me.
As for the quests, they're split into Quests and Campaigns; the latter usually requiring more than one person to complete and rewarding better items/more XP. But overall a quest is a quest in any game... whether it be "bring me a head", "kill a dragon" or "cook a pie" so I'm not sure what you'd consider an "other" quest ?
Having said this, I welcome Aion to fill some time whilst I wait for 2010's WoW Cataclysm and Diablo 3!!!!!!
