I've been a lot into RPG's when I was 15, but there was no MMORPG's then.
Nethack
Loved Wizard, it was incredible. Strongest spells from afar, astonishing variety of abilities. *Had* to use them unless wanted to kill it. Ohh fireballs, identify scrolls, invisiblity, *TELEPORTATION*, gasp.. ohh.. the game style was almost completely forward-thinking, and it had to be. Wizard didn't have many remedies to any problems when they had occured, but it did have some.
Priest, YAY! Healing extrordinate, remove curse! Instant curse detection! It was able to withstand most problems resist them. It promoted a little more care-free playing.
Fighter, samurai: just hit and kill. Didn't need anything more elaborate for most fights. Incredible carrying capacity, so they could use the hardest armour and carry the most stuff. And when stuff is useful in combat, it's just great to be able to carry a lot, even for selling the stuff to shop. Apart from being able to carry a lot of different useful items, they had themselves restricted abilities. No healing or blasting abilities, and no control strategies to speak of.
Zombiemud
Played via telnet.
I absolutely loved mage. This is a game where you are able to switch classes with a cost of 1-10% of total character experience. It made absolutely ton of damage in short time, in lower levels. Then in started lacking, and it was bad. It was so weak and didn't have anything else than fast damage. It couldn't kill big monsters, because it was sooooo weak and unable to defend.
Then druid. THe druid was the hocus-pocus of astonishing, devastating abilities of the most incredible kind. Tons, tons of abilities. All miniscule, all elaborate. If one invented a good way to use them in combination, truly game-breaking abilities could be done. Things that no-one in the online game would believe. Summoning a right kind of helper, putting the right kind of protection spells on them, using the right kind of this, that, this, that, and good fight tactic, the druid was able to kill monsters that usually required a whole *GROUP* of people. It was so damned awesome. I often fought in the same areas, where other groups of 3-5 people were partying.. it was possible to work so well with carefully engineering the character and what you do. GREAT!
Wow
Fighter: charge, strike, whatever, blah. So bad and limited, hated it when leveled it to 27 or so. IT was my first character, so then I found out I had played it wrong.
Shaman: ahh, so many tricks. It could do anything. It held a huge advantage compared to many others before the end levels. Again with careful planning, using of all tricks of different sorts, and inventing novel places to do the tricks in, incredible feats could be accomplished. People would not believe that I could kill elites 3-4 levels higher than me in many points. I just had to find a situational strength in my character and a situational weakness in another, and the tricks were there.
It was also incredible to participate in groups, awesome. At some levels I thought I could do anything. Switch from healing to tank and to blast. Whatever errors other made, I could compensate. I was too eager to break the order myself, so I often got the groups into troubles, lol. That was before I began to play it with more discipline.
In the end game shaman lacks important bag of tricks, that of avoiding snare, being rooted, slowed or crowd controlled, and shaman can't do such tricks by itself. Shaman becomes a weakling, which I have hated.
It still made the most melee damage of any class when fighting monsters, according to my logs. That was when I optimized it. But it is so bad against players, with my knowledge. It was also an awesome healer, which was funny in pvp and pve (monsters). But I hate how the restricted roles don't promote versatile gaming style. So I stopped playing. Had it at level 70 with a few epics.
Rogue, Mage, warlock, paladin, priest
played each to level 6 or 8 or so (1-3 hours of play) then bored.
Druid: played some 15 hours, then bored. It was interesting tho to some extent.