Eternal Sunshine was interesting, even though it swiped all its ideas from Philip K. Dick I enjoyed it. Before SUnset was painfully bad. Kill Bill 2 was one of the worst things I've ever sat through. Have no desire to see another Mike Leigh film. I was pleased with the wins Sideways and Aviator got, but found both to be lesser films from their makers.
The only movies from 04 that will join my alltime list were Million Dollar Baby and Collateral.
As to Before Sunset perhaps you're not a fan of Linklater's style. He has that laid back this-is-happening-now improv groove that leaves lots of people cold. One of the keys for me was that those two characters aren't all that interesting or nearly as smart as they think they are. The movie knows that. Lesser Scorsese is still better then most directors at their best. I forgot to mention 'I Heart Huckabees' and The Life Aquatic with Steven Zissou. Not entirely succesful but ambitious and honorable.