I'll second the vote for Horse Trailer World - great way to do some surfing and comparison shop without having to put on the miles.
We went for a 4 horse for the long term - with the prospect of kids in the next 10 years who could be riding as well as the ability to take another couple along with us. For the most part we seem to haul 2 at a time, though!
Around here, all aluminum is the favored construction due to the salt on the roads. Given the desire to have the blend of economy and quality, the favored brands around here are Featherlite, Kiefer Built, Sundowner, Exiss and the like. 4Star seems to have some real quality built in the units I've looked at, but with a bit more price, of course. We don't see too many Bloomers up here.
Do some looking around, figure out what you like and don't like and try to find a dealer you can trust if you're going new or anticipate the need for post-sale support. Ask lots of questions, too.
We ended up with a Kiefer 4H LQ with an 8 foot short wall. Bed, couch, shower, toilet, sink, stove, micro, etc. - you know, the essentials. We spend a lot of time in ours going to shows and horse camping. Been very happy with it. With Kiefer, it was interesting looking at models over the years - they've made quite a few improvements in their design and they're still pretty affordable. We looked at quite a few Featherlites and I would've been happy with one. Budget was an important driver, so we didn't spend too much time with the higher end brands or models. Fun to dream, though!
Patrick