intermediate level instruments

I see, there is a big difference between the situations in the States and in Germany! In Germany, public schools are not very "musical". Only a few Gymnasiums spend money to teach musik in connection with an own schoolorchestra.
In Elementaryschools childeren have no musical education or only C-soprano-recorder. If you like to learn an instrument like horn, you can choose between a lot of Musikvereinen (wood-brass-percussion-bands who plays traditional music), or a Posaunenchor (brassbands of the lutheren church) or you visite a privat or county-own musikschool (they only teach music). Most of all hornstudents begins on a Bb-horn! F-Horn is very rare and like a "special darling" for "at home". Doublehorns mostly are used only by students, who learns at a privat hornteacher (orchestra hornists). The reason for that is: Germany is "Bb-horn-land". For example: In our Posaunenchor, I use a Bb-horn, because all other brass is in Bb, too and its sound mix better with trumpets, trombones, tubas and tenorhorns and so on. But in our Hornquartett I use a single F, because we like to have a fine, original hornsound. But with this praxis we are still standing "alone". In Austria a lot of hornquartets play on single F-horns, specialy on the viennahorn.

I have played Holtons my entire horn playing life (40+ years). I have briefly tried Yamahas and Atkinsons. Yamahas did not work well for me and the Atkinson is about as close to the Holton quality that I've played. I know that the H179 is their most popular horn, but I have always preferred the H180. I have played a couple of Merker Matics and they are also excellent horns. Probably, the best Holton I've played was the Barry Tuckwell model, but that one is very expensive. There will be good and bad instruments from every maker out there. I never buy a horn that I can't try out first. In other words, I would never buy a hour that I couldn't turn down if I didn't like it. If at all possible, buy a horn from somewhere that has 2 pr 3 to choose from and buy the one that works best for you. If you can't find one you like at one place try another place. Don't ever settle for the best one available.
Good luck on your search.

@ Green Hornist:

Yes, You are right! Never buy a horn without testing it. In Germany we say: "Kauf niemals die Katze im Sack!" (Never buy a cat in a sack.) That means: Dont buy blind.
The Tuckwell 104 or the latest 105 is a very fine Horn, whats much more better than the rest of the Holton range. And the problem with good and bad instruments in one manufactors series is well known. Specially Alex has big problems with that. But wether someone likes a horn or not, is a decision of the players feeling, specially at the level of expensive instruments.
But in the last few years, american factorys have big problems with the quality of their instruments. The reasons are well known: Strikes, jointventures and so on. In our Posaunenchor, we ever played V.Bach Trumpets. But you cant get one nowadays! And if you get one, mostly its bad! (Trombones, dito.) No spareparts are available! And if they deliver, its nerver just in time. Take a look at Conn: The older ones (E-series) were the best ones they ever made! I visited the Frankfurt international music exhibition this year. At the stand of Conn / Holton (Conn- Selmer) they offered only four horns! You'll be kidding! In past times, Holton presented their complete range! I chatted up a teammember and she told me:"Sorry, no hornexpert is in, they are at home." Sorry, thats a joke. At one horn at the stand, the strings at the valves were broken, at one horn the changevalve was jamed and only two horn were ready to play. How they wanna sell a horn?!

The suggestion about rental is almost good - except that instruments rented are usually beginner-level, rarely intermediate and never more, and the buyout prices are usually inflated. However, it's very true that you should try before you buy. So here's a thought: find a horn teacher if you aren't taking already, and tell your teacher you are still looking for the right "serious" instrument. If you have anything at all to practice on, are a musician, and don't disrespect what you're doing, you may get amazing help and support.

I'm speaking from somewhat-sad experience here: my long-ago horn teacher (God bless you Tom Murray) let me borrow his Alexander 103 for several months. It wasn't the right horn for me, but I was and am awestruck that he entrusted that to me. I wish I had had the sense to keep looking for the right fit (eventually an 8D), but hindsight is 20/20...