Enough space (1 by 1.5 m, 2.5 m tall), fully enclosed stall.
A sit-down toilet
A box to throw menstrual pads into
A toilet brush for cleaning
A coat hanger at eye height
Plenty of toilet paper, duh
As an accessibility, cleanliness, and efficiency bonus, you could also add for bigger and/or public toilets:
Lowered seat, shuttable arm rests
Foldable changing tables
Hand cream to clean hands (or a proper sink, not a tiny ass one; the towel should be above the sink. Also, if it’s a sink, it shouldn’t be in an inconvenient spot).
The lights turn on when the door is locked, and turn off only when the door is unlocked.
Don’t forget a box to throw menstrual pads into!
Imho, the ideal bathroom should have:
As an accessibility, cleanliness, and efficiency bonus, you could also add for bigger and/or public toilets: