Personally I'd avoid M-Audio.
They do not have the best reputation for updating their drivers - sometimes they've lagged years behind new versions of Windows.
In the "inexpensive but pretty good" end of the market the lower models in Focusrite's range are generally well regarded.
At the more expensive end of the market RME are regarded as very good, with some of the best hardware and drivers going. Focusrite's higher-end interfaces, MOTU and Tascam are also worth a look.
If possible get an interface that uses a seperate power supply, not one that's powered by the USB bus. USB power makes mobile working easier but not all USB sockets are equal, some don't supply quite as much power as they should.