Own both and really like both. My tone is largely based around an old Marshall JMP-1. Was easier to get those tones in and out of the Kemper, and it was also a breeze in the AxeFX by shooting an IR of my cab (which is like profiling the cab only) and pairing it with the JMP-1 model in the Axe (which is dead on accurate to the real thing).
So, for basic tone each are brilliant. Feel wise, the Axe worked better for me as it had a little more immediacy in my particular case.
If you are choosing between the two, the only thing I'd really suggest is to think through how important effects are to you. If you want more than just good set of basic effects, then the Axe gets my vote. If you are good with a basic set of excellent quality effects, the the Kemper is much easier to work with IMHO.