I've played just about all of these except yamaha and have found that you really cant go wrong with any of them. I probably played the 5000 but dont remember a a strikiong difference between that and the 5050. ( if a member more familiar with the miraphone models could chime in that would be great.) But my section mate owns a 5050 and its a wonderful horn with a great sound. Although it is a tank of a horn! I play an E1 and love it. It is a toss up between a E1 setup like mine and a 5050, although the 5050 is large and open it felt to present ever so slightly more "resistance" to the face than my free blowing E1. I played the E3 at TMEA and was very impressed by it overall. If I were to get one myself it would need to have the sterling silver bell. Every horn I'v played of Adams is really phenomenal, but my taste in tone truly lies in what I get from a sterling silver bell. E2 is a close second to the E1 sterling silver setup in my opinion.
I agree with Dave in the additional consideration of Besson and Wilson. I personally liked a new Wilson over a new Besson just as far as preference goes, but both have great horns. If i got a Besson though i would rather have a Sovereign 967 over a Prestige any day. I think they sing more for me. Plus now you can order one with a tuning trigger!!!
Adams E1 SS, Gold Brass Body .6mm DE Euph N103 Jcup, J9 shank
Meinl Weston 2141 Eb Tuba PT 84