If you choose the the korg nano over the novation because of size you will definitely don't like the APC40 because it's BIG.
I have used the Novation MK1, the Novation MK2 and now I use the APC40, and I love the APC40 because of the many buttons, and rotary encoders winch will reset when you press the reset rotation button, the channel brightness sliders you can move 4 sliders with 4 fingers etc etc.
I have a touchscreen but I hardly ever use it because I find a mouse more easy, so it all about your own preferences and how many control you want.