I use and am satisfied with my Road Morph-G; the gauge is reasonably accurate and having a hose really helps to prevent damage to your valves. I use it for mountain bikes too, even though there is a mountain-specific model also available; lower pressure/higher volume I imagine.

I have avoided CO2 because once you run out (second flat or patch failure does happen) you are stuck, air is free, and pumping is good exercise, which is part of the reason I ride anyway.