Beethoven is among my very favorites, and his piano concertos and violin concerto are monumental works, IMHO.
I agree that once Beethoven came along, music changed dramatically, but the musical shot heard round the world was the "Eroica" Symphony. Once that came around, nothing was quite the same.
Beethoven's string quartets are my favorite Beethoven. But even his worst works are interesting.
I love baroque and medieval music.