Voted 2000 purely because that was only my second year watching WWF. Would've voted 1999 purely because that was my first year and I loved everything about it, but tbh you can't compare any years of the Attitude Era because they were close to the best years we've seen in Pro Wrestling.
2000 for sure. The roster was super strong from top to bottom compared to previous AE years, Rock and HHH were at their peak and for the first time in that era the in ring work was consistently high quality across the whole card rather than just in the main events. It had the perfect balance of great storylines and great wrestling.
After that i'd say 1998 easily takes 2nd place thanks to the birth and peak of the Austin/McMahon feud and the sheer amount of memorable "holy shit" moments its had. Then its a tough call between 97 and 99 for me, 97 had better wrestling and 99 had better angles. 2001 had many of the qualities 2000 had at the start, but I only consider the first half part of the Attitude Era, plus the Invasion angle fucked most of the year up and killed a lot of my interest in wrestling.
1999 had great storylines and some good matches. Stuff that did leave me on the edge of my seat.
2000 had the rise of HHH as a heel and his matches with The Rock were(still are) great to watch. Kurt Angle/Benoit matches