The M-Audio Keystation Pro 88 Controller Keyboard is one of the best MIDI controller I have played on both in the studio and live on stage. The full size velocity, sensitive, hammer action keys and the array of knobs and sliders give you all you could need to preform just about any style of music from classical concerto piano to hard trace hovers.
Build construction is great and its weight makes it stable even under heavy handed playing (as long as you have a solid keyboard stand). Knobs and sliders are smooth but not automated but at the price point not a deal breaker.
Although this model has been discontinued, the M-Audio Oxygen 88 USB MIDI controller looks like a worthy replacement.