I see meny stronk ragers in here.

On topic, I think gladiator is one of the easiest.
They have high Damage even compared to some pure damage classes, yet the ability to offtank in groups.
They can wear the highest defence armor (plate) and are hence can take alot of damage, whilst still dishing out a large amount also, this makes soloing rather easy. You don't have to worry about mana recharges either.
People say that gladiators need potions because of there lack of regenerative skills whilst solo'ing, but so far I havnt had to use many, granted you may need to rest every 5-10 mobs, but thats only about 10 seconds, compared to some other classes thats nothing.
If you don't fancy it, templar is (One of) the lowest rolled characters in most servers, and the lack of them makes getting group invites very easy for templars.
Whilst there isnt a shortage of clerics, its not hard to find a group as one.
From what i've seen so far, chanters can't "Buff", they're "mantra's" simply give you buffed stats ONLY when your in a group with them, and within a very short distance, so dont think you'll be making much kina for selling "buffs", as in some other games.
I cant talk for any other classes as I havnt played them, but good luck and enjoy Aion! =D its a very nice game, especially after level 15 +.