Tchaikovsky is musically a very easy concerto, thats why its played so much for competitions because it is also quite safe once you get the notes. Also, if you can play the Chopin near perfect, I would encourage you to do so (if they are reccomendations for you). Also if you can master Beethoven 3 it is actually a very respected concerto if also played to near perfection. My favorite competition concertos are as follows:
Liszt 1
Liszt 2
Totantanzz
Rach1
Beethoven 3
Mozart 9
Tchaikovsky
Prokofiev 3
Prokofiev 2 (if you can play it!)
Khachaturian
Definate NO's
Rach 2 and 3
Brahms 1 and 2
Maybe's
Chopin 1, 2
Beethoven 2, 4, 5
Most Mozart
Bartok 1 2 3
Prokofiev 5
Gershwin F, Rhapsody in Blue
Just my thoughts...
SAM