This power vs. torque debate can go on and on... because neither side is wrong.
If you could only find out one thing about an engine, the HP is definitely more important than torque. It's just physics, and HP includes torque. However, to really get to know an engine, it's the area under the torque curve that matters. (it's still some form of average power, since width of the area is rpm and height is torque)
We'll just have to wait and see what the graph for the new M3/4 looks like.