I used to play mostly romantic pieces, but after playing Beethoven's Waldstein Sonata, I really want to play more Beethoven and Mozart. I'd really like to play Beethoven's 4th Concerto (I like it more than his fifth), but I think it's too long for me to have a realistic opportunity to play it with an orchestra. I really don't know much about Mozart's Concertos.
What is everyone's favorite? The only one I'm somewhat familiar with is the 20th, and I really like that one.