This probably has been done to death but I'm just curious, and bored, and this forum probably needs air breathed into it constantly -.-
I'd say because of the healing (and damaging) capabilities of Necs and SK's that they're top tier material. Necs with max AR can pact and not take damage right? To good. Bards too for lvl 16 sow, a low lvl HoT and PoT and some sick nasty buffs.
High tier would probably consist of Monks (self heals and good stat increase CM's right?) and rangers. Rangers for them kiting abilities. I think Mages would go here too, that or upper mid tier only because their pet is their life.
In terms of efficientcy(sp), I'd rank Healers low (but not as low as rogues) because they can probably tank a highish lvl but to kill it would be a pain. Rogues would be near bottom because your spike damage (I forget what we called it back in the day, burst?) and how much you can do is off set by crits. Crits hurt (eventually) and having to take them every time (even if you could avoid a quad) would still break you.
I am not sure about pali's ench's or wizzies cause I never played them (enough). I guess palies get nice undead dealies around 46 but that's a long time to not be good. Alchs, IIRC could be close to rangers, with kiting and all, except I don't think they have a heal like rangers do.
This leaves us with warriors. I'd say they're a wild card. I think it depends on how you build them really. More damage offset with less defense or vice versa? The only thing holding them back is a good self heal (unless bellow got changed with class balancing. a 5minute recast heal isn't good -__-).
Discuss. I'm tired and bored and really miss this game. I hope my account problems get sorted out soon.