There are basically three trumpets that are really great and I recommend for my students.
1. Bach Stradivarius 18037 or a variation thereof
It should have a #37 bell. (Printed on the bell itself)
Some variations of this horn that are also good are:
1a. the anniversary model
1b. The Artisan model - what I play
For Bach, you can do silver or lacquer. I prefer lacquer, but a lot of people really like the sound of silver.
How to read Bach:
180 is the horn model. 37 is the bell number. LT is "lightweight", kind of designed for jazz and commercial playing and I don't recommend that for my high school students. LR is reverse leadpipe, which is just fine if you like that better. If there's an "S" that just means its silver.
It may say Bach 18037, meaning 180 horn and 37 bell.
Or it could say LR18037S which is the same as above but with a reverse leadpipe and silver.
2. Yamaha Xeno
On the left side of the second valve casing it should say YTR8335. There's also a YTR9335, which isn't as great of a horn. Watch out for that.
If the shop has standard leadpipes and reverse leadpipes, try both to see what you prefer.
For Yamaha, silver is the only way to go.
3. Shires model A or B
These horns are all handmade and all very nice, but they can play very differently even within the same models. If you go to a shop with Shires, try them all and see what you like. They just made a Q model that I haven't tried yet, but they're geared toward intermediate players. I'm sure they're fine horns, but I would stick with the pro-level horns.
For Shires, I think the silver ones are almost always too bright. Try lacquer or raw brass.
Note: A lot of salespeople will tell you that Jupiter makes just as good of a horn as those three for cheaper. It's not nearly as good. Please Please Please don't buy a Jupiter.
Where to buy:
Most music stores will have the Bach Stradivarius and the Yamaha Xeno.
If you want to try some of the Bach variations or Shires, you'll have to go to one of the better shops. The two best shops to try lots of great horns are:
1. Houghton Horns
They have a GREAT selection as well as an amazing staff.
2. The Music and Arts store in Lewisville. Unlike most Music and Arts stores, this one is geared toward high level instruments. They have a pretty good selection.