I was playing the original Everquest back in the day and I had been checking out other games like DAoC, AC, AO and probably a few others. I was visiting Betawatcher and MMORPG.com regularly looking for something new when I came across that original Cryptic video for CoH. You know the one where they have that hero that jumps from a lower level building to a higher one then just flies off the camera at you at an angle, and I was completely hooked from then on.
I got into the beta, I pre-purchased the game, I played it all through its life, barring a couple of breaks for real life, and its last year I thought it was the best it ever was. There was so much total content and so much new content released when Freedom launched I was in heaven. I have honestly never had as good a time in an online game as I did with CoH and the only game I played for a longer period of time was EQ but only because CoH was cancelled or would have taken the top spot on that as well.
One of my favorite things about CoH was that while it had tremendous depth, it never seemed overly complicated to play, at least, not like games like EQ (though that game is still around 15 years after launch). What am I playing today. EQII actually. That and some Champions on the side.