I'm an old fart; I marched in the 70s and 80s, so I'm a little biased.
For me it was Dvorak and Brahms for the big stadium-rattling power chords, plus something "fun" for the crowd like this (youtu.be) and this (youtu.be)
I agree with the early 2000s being a peak though - before props and amps, but an increase in 'themed' shows. A lot of pieces were given new life, or new interpretations.
Before kung flu shut it down, there was a resurgence in more complex pieces being put on the field, non-stop high-energy shows, and insanely complex solos. Everything from Pat Metheny to Pink Floyd (dailymotion.com), even some Arcade Fire (youtu.be)! (Proud papa moment, my son is in there somewhere.)
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