The attitude era was overrated to begin with. I woudln't even call it the best time. I enjoyed it, but at times, it was way too chaotic, and it had an extreme lack of main event depth. But no denying it was the most succesful time, and I still enjoyed it. But my favorite era was the 2002-2004ish era. Despite losses such as Rock and Austin during this, we had several good things. Kurt Angle and Eddie Guerrero in their prime, Evolution at full force, a new, healthy HBK, Brock Lesnar, Goddberg, 3 of the best Wrestlemania (18,19,20) and overall, just a cool time. It also still had a lot of attitude era traits.
I can't choose a specific year, cause it was basically just the whole 2002-2003 thing blended together. 2006 is a close second though, like you said, it was an exciting time as well. DX, ECW (the whole excitement at that time was great), Edge vs Cena, and WM22 was great. But my favorite period still has to go to 2002/2003.