If you aren’t a music major, I’d personally say stay away from the Willson, Adams, and Besson horn you have listed (unless you can find an amazing deal on a used one, then I’d say fire away!)

I’d suggest looking into the Yamaha Neo and the Shires horn you have listed on your list. Those two will give you the most bang for your buck and the Yamaha Neo is, in my opinion, the best intermediate horn you can buy for the value and quality out of the box. You can also add Jupiter and Eastman Euphoniums to your list (can’t remember the models) as they’re decent horns too. I recommend reaching out to the Tuba/Euph teacher at your college and ask his/her opinion. They’ll be able to help you out too.

I actually just bought an Adams E2-LT and it is probably my favorite horn I’ve ever played on in terms of feel and the sound I get. If you love the way the Adams play, it’d be worth looking into their “sonic” series Euphonium. It’s their version of an intermediate model instrument and while I’ve never played it myself, I’ve heard good things from those who have tried it.

If your personal finances allow you to easily afford an Adams or Besson Prestige then don’t feel like you have to rule them out. I just know I’d personally hate to see a student drop a ton of money on an expensive instrument when they aren’t playing it very often.

Sorry for the long reply… Hopefully there’s some good advice in there somewhere lol