For me, it's gotta be one of these AC2 Tactician - This was basically an engineer who could build both high DPS turrets and walls. So you'd team up with other players, find a bottleneck, place some walls there, place a turret behind it and have the other guys pull high level mobs. The mobs would chase them but get blocked by your walls which they'd have to take down to get to you. But the turrets would blast them to death before they could make it. Most fun I've ever had with an engineer type class AC2 Juggernaut - This was a melee class with one killer ability. You could throw your weapon and there was a chance it would knock 20% off a mob's health. So in a boss fight, where a boss had 30,000 HP and everyone else was doing 100 dmg a hit, you could use that ability and knock off 6000 dmg, shorten the fight by 30 seconds, and feel overpowered all with the push of a button. AO Fixer - This was the hacker class in AO that was very cool in concept. It had access to its own vendor and could teleport to a zone known as The Grid, which was kind of like a Cyberspace fast travel. It also had the ability to use a rare type of armor that made your character blue called Grid Armor. The armor had 0 protection but raised evades to a ridiculous amount. The idea was when wearing Grid Amor, the Fixer was phasing between the real world and The Grid. If you had the armor and a high enough skill level, more often than not nobody could hit you. WOW Rogue - My favorite class to mess around with in PVP. I used either a stunlock build or an ambush build to kill. If I couldn't kill, I'd just pop evades and vanish. When I was bored I'd use distract and sap to stop other players and make them run around and look for me. SWG Architect - Best crafting class I ever played. Survey the ground, claim the real estate and place harvestors to get resources, place factories right next to them to mass produce house deeds and furniture, build a house and turn it into a shop, put a sign on the outside, put all the furniture you've created on display in the shop, hire an NPC to run the shop and open to the public, log in few days later and everything in your shop is sold out and you've made a ton of money. This is why I hate modern MMO crafting. It's gone from fun stuff like this to just gather resource, click button, create trash nobody wants.