I think we can do better. Many of the current designs are CLUNKY and not much fun to use.
My choice would be:
1) Control switching by lightly pressing a clicky.
2) Default mode with two levels, low (lower than most on market now and no more than about 7 lumens) and 100%.
3) Rotate the head to go to a setting with three modes,
4) Choose from three user defined modes, such as low, medium and high, ideally programmable.
5) Let the user choose which stage would come on first. For me, that's low.
6) Forget the silly strobe, SOS modes, etc. For that, a "boyscout" light in khaki green is the answer, not for most typical EDC users.