had both, so here's my thoughts:
axe-fx ultra: great unit for effects. amps/cabinets are good, Ownhammer IR's make them better. no true-z input, so feel factor is not the same as 11R. no usb or headphone jack, so you need to have an interface to listen to it or record it.
eleven rack: feel is VERY close to real tubes. amp tones sound/feel genuine. limited effects, but what it does it does pretty well. has true-z input, usb, microphone input. no 3rd party IR's unless you use an Epsi. with an Epsi the tone is anything you want it to be.
i had the axe-fx II also, and though i thought it was on par tonally with the 11R plus it had more effects and routing options.....i'm back to the 11R. the 11R is just easier to tweak without getting lost in options.
also, since i had hundreds of quality presets in the superpack it just made sense to stay with it rather than reinvent the wheel again with the axe-fx.