Until last month I was using the Korg MicroKey37 - it's about as basic as it gets and cheap as chips but it served me well until I felt I needed more from a controller keyboard.
Since last month I've been using the Novation Impulse 49 and couldn't be happier with it.
Automaps control of 3rd party plugins appears (so far) to work flawlessly, the keybed is definitely a step up from the little Korg; not just the full sized keys but (as near as damn it) semi-weighted and with aftertouch as well; so much more expressive.
Build quality as far as I can tell (so far) is above standard (and all midi controllers are built cheaply if we're honest) and it looks and (more importantly) feels great to play.