I can't agree more, get a 50 size machine from the beginning. WHY? Because this is where you will end up in 6 months. Save the money up front and get it early. The 50 will be a fine machine to learn on as well. The nice thing is the parts are ususally the same as you get with a 30.

My choices would be in this order:
Sceadu Evo 50
Raptor 50

I would not take a nexus even if it was given to me. I don't care for the Hawk, lots of reasons. No nothing about hte Kyosho so can't help you there.

Good luck!