Depending on how you define raid, I don't really think ARR has any yet. I just see them as dungeons. Crystal Tower I'll consider a raid though.

As for my most fun raid, that would have to be in DAoC a few days after the introduced the 3 dragons into the game (1 pre realm). My guild and some allied guilds got around 150 people together, and made our way to the dragon. We discussed some rudimentary tactics (there was little to nothing known about the fight), and eventually ended up just running towards the dragon. The moment we got in range, the dragon flew up, cast a massive fire based AoE and 1-shot all 150 of us