I'd say 2000 or 2003. I'll go with 2000 because that was a stacked year in all categories - great wrestlers/workers, great characters, great storylines, was probably the best overall year for PPVs, etc.
Even with Austin out, you still had Rock and Triple H in their prime. This is the year when Triple H shined the most as a heel. He was drawing mega heat after his pairing with Stephanie (the McMahon/Helmsley Era where they "ruled" Raw was an underrated but successful gimmick) and his retirement of Mick Foley (great feud that really put Triple H over the top as a long term main eventer) and people even pelted the ring with garbage when he became the first heel to walk out of Wrestlemania as still the reigning WWF Champion. You also had the Kurt Angle/Triple H/Stephanie love traingle during the Summer. Shame it ended very anti-climatically, but then again, I didn't really agree with their original idea (Steph sides with Kurt Angle and turns HHH face in the process) anyway. It's kind of funny how heel/heel feuds tend to work the best when it's two guys feuding over a woman (for another example, see Sherri Martel being struck on both Shawn Michaels and Rick Martel in 1992.)
You also had a very solid tag team division: Edge and Christian, APA, Dudleyz, Hardyz, Too Cool, T&A, etc. Austin coming back to wreck havoc looking for who ran him over, Mick Foley as Commissioner, that great Rock/HHH Iron Man match, Undertaker returning as the humanized American Badass, Big Show's light hearted gimmick with imitating people, the 24/7 rule of the Hardcore title with Crash Holly was entertaining, Tazz's debut (though he wouldn't end up doing much, unfortunately), the Radicalz debuting (there's a strange story to that, but here isn't the place to get into it), Rikishi dancing with Too Cool was fun to watch, Right To Censor made for a unique group idea, Kaientai's amusing "evil/bad english dubbing" gimmick, you had a good light heavyweight division, etc.
It's a shame not many people know the name Chris Kreski, because he was the main writer who took over for Vince Russo in late 1999 and was behind 2000 WWF's brilliance, booking wise.
2000 might just be my favorite overall year. I'd say in no order though that 1997-2000 and 2003 were my top five favorite WWF/E years ever.