The X3 M looks fantastic I must say, although perhaps a bit tame from the front.
The X4 M however......well.....hmmm....I got to say the GLC Coupe looks much better.
Maybe the colour showcased may affect your pov, if you allow me to write this. I saw the X3M and X4M 10 days ago, X3M was in black and X4M in donington grey. Of course ligthing conditions weren't the best, but the X4M in donington colour faded out the X3M standing next to it. Then again probably this would be different under sun light.