Bad. Levers:

Bad. Buttons that are located in a weird place:

Bad. Buttons that make fingers bleed:

Good. Those that aren’t any of the above:

Excellent. Those that remember being pressed:

Obviously, all buttons should be responsive to touches in gloves. There should be no buttons on trains that go only through a closed space.

Added on May 29, 2020: Buttons should not be used during the coronavirus pandemic.