Hi Jonopark,
The Rebel and the C4 are completely different kites. They are both excellent high quality kites made by two of the top manufacturers in terms of quality and performance.
The Rebel is grunty, quick, smooth, very boosty, and a pretty good wave kite. The Rebel is lousy for looping if you want a good hard downwind pull. I class the Rebel as a freeride and wave kite and is at the top of it's class.
The C4 is a less grunty until you build up forward airspeed over the canopy, it is quick, smooth, precise, boosty in a "C" kite kinda way, and is a half decent wave kite due to it's speed and agility. It is a weapon of a looping kite. I class the C4 as a freeride and freestyle kite which works in the waves too, and again is at the top of it's class.
Which kite would suit your needs can only be answered by you. You need to know which style will suit your needs best. There is no bad choice, both are excellent. Price is similar when you take into account the size differences to get equivalent power.
I'd suggest dropping in and grabbing a demo on the ones you are into, then make a decision based on your thoughts rather than the thoughts of others. They have different needs and styles to you.

DM