I voted a mixture of the two. I'm more of a social gamer now in LOTRO (as I was in DAoC and WoW). I'll spend time with my kinmates (guildmates), help strangers when they're low on power or morale, etc.
There was a time when I was very anti-social in Ultima Online. It was a rush. I had a murderer, and the works. I'd often strip my mage of armor and items, except for enough reagants to cast two spells, then run them in town, target someone's pack mule with a delayed spell, then fire another insta-cast one to kill them in two hits before the guards killed me. It was the sweetest bit of anti-social behavior I experienced. I did the same with low-levels on my murderer who wondered a little too far out of town. I was a ganker before the term "ganker" was even created and used.
But now that I've matured, I find much more enjoyment, satisfaction, and ethical comfort in helping others in any game.