The 25-key version (which I have) has a joystick that controls mod and pitch. Not my favorite part of the controller, but the 37-keys and up versions have the wheels. It also has built in sustain and arpeggiator buttons (the latter acts more like a note repeater).

I’ve had great experiences from both the Korg nanoKEY and Korg microKEY controller families, and they are both portable.

Thank you Eowyn!