Pick somebody that has done what you want to do, whether that's orchestra, solos, jazz, chamber music, music education, etc. Also many of them have cd's available so that's a good way to find whether you like their sound.
Go and meet the horn professors and take a lesson. Whomever teaches you the most in that first lesson is the winner. The reputation of the school doesn't matter as much as the individual lessons you will get.
Think about going to a college or university, not a conservatory for an undergraduate program. Just in case you change your mind about music (and many students do) you'll have a much easier transition to another major. Also think about getting a music education degree first, because you'll have much better odds of getting a job after college, and even if you do become a famous performer you'll spend most of the day teaching.