Of those listed, I'd say go for Schoenberg or Beethoven's 5th. Either way, you want to have it down perfectly, but if you play the popular one (as the so called "Emperor" or Grieg's concerto) you want it better than perfect. Schoenberg's gonna get you a kudo or two, imo, simply because of what it is. But, of course, you can't let that carry your rating--you're still going to have to do a bloody good job on it.
Other than that, check out Scharwenka's and Sauer's concerti, both of which are on a Hough CD that I just purchased--excellent, underplayed works, both of them. There is also Paderewski's and.....even Moszkowski's would be kind of fun. Haha, how about that? I think that would be a wicked one to play at a competition. For something else a *little* different, why not try Saint-Saens' third? I love the 5th SS concerto, but the third is incredible....but then it seems like few people agree with that.
Well, those are just a few suggestions...
Btw, I had to grin at the mention of Sorabji....I have to say that's the first time I've heard of someone considering playing one of his works at a competition! Have you tried playing one of those Pistaches yet? They look insanely difficult, but possibly marginally easier than they look....btw, thanks for that Habanera sheet music...you've satisfied my curiosity and also nearly gave me a heart attack...both at the same time!