If you can fly a Hiller you can fly anything.....
If you intend to fly commercially, you want something that is used commercially, and is cheap. The insurance companies don't care what the hours are in and it can be the scruffiest out there (as long as its safe of course). However, companies do care if they are faced with converting you on to something different.
Now, as to the title of the thread, the best one to learn in is the Bell 47...... but that's another thread.