Rotterdam would have been a much more sensible candidate than Amsterdam (very nice skyline versus a very meagre skyline).
Anyways, out of the ones you selected, in my opinion Frankfurt and Paris have the most mature and impressive skylines. London and Warsaw are the runner-ups with loads of potential to bridge the gap.
Anyways, out of the ones you selected, in my opinion Frankfurt and Paris have the most mature and impressive skylines. London and Warsaw are the runner-ups with loads of potential to bridge the gap.