If your budget limits you to one helicopter, the 50 is your best bet. If you can afford more than one, then a combination would/could be beneficial. I own a 450 class, a 50 class and a 60 converted to 90.

When I'm practicing maneuvers, the really new stuff I try on the 450 first, then if I'm succesful, I try it on the 50. Then when I'm comfortable I do it with the 90.

Rafael