Alright, a Reel Big Fish fan!
I hold both instruments in the same respect but I would recommend the Trumpet, though the trombone is essential to most bands, you can go a lot farther with the Trumpet. I know a great trumpet player who is amazing and yet there is still so much more he can learn. Plus, the trumpet is easier to incorporate in many types of bands and is a big thing in many Ska bands.
Hoped this helps.
