Of years since I've been an actual regular viewer, probably 2002, since it was the first full year I watched...2001, all I have memories of is a small portion of Survivor Series-end of the year, so not enough data for me to accurately assess it.
Years I wasn't a viewer but have seen all kinds of clips of? Oh, man...that one is tough.

1998 seemed amazing, with Rock finally starting to come into his own, but he totally owned 1999 & 2000, so I guess its a 3-way tossup between those years for me.