Worst shower by far was in Coober Pedy, Australia (forgot hotel... certainly not luxury). Shower head plugged by hard water deposits with the exception of three holes. If you stood in the center all three individual streams of water missed you.

One of the best is a Park Suite at the Park Hyatt Tokyo. Nothing fancy, just volume, volume, volume + pressure.

Also, in my humble opinion, it is hard to beat a good old Speakman Anystream brass shower head with flow restrictor removed and high pressure to back it up.