Of the big fraction of the episodes of The Simpsons I've seen, the best episodes have came from Seasons 5 and 6. My favorite season of the show is the controversial Season 12 which conrains my absolute favorite Simpsons episode "New Kids on the Blecch," which is the episode where NSYNC and Bart starts a popular boy band.
But I have a warped view of the show as I have watch it out of complete order and feel the show has had a share of good and bad episodes, however the highs in the earlier seasons are higher than the highs of the later seasons...however I tend to avoid the episodes in the 20's and 30's.
But, yeah I consider myself a fan and I have always been a big fan of the Simpsons universe and its characters and I loved playing the 2000's video games like Hit & Run growing up, but I don't consider myself a Simpsons purist by any means and I've never had a strong bias towards the "classic era" of the show which is usually considered to be first eight or nine seasons.