No less than a 4-channel of some sort, if you are serious.

The co-ax will hover very well. So you can get it in the air and around the house with a little bit of effort. With the co-ax you can learn orientation (tail-in, side-in, nose-in).

The fixed pitch will be more of a handful, and there's a learning curve in getting it to just hover. The FP will better prepare you for CP, but you will crash a replace parts a lot.

What's your frustration level?

-Dave