webOS webOS webOS
webOS had a hardware sensor for gestures and made using the phone so intuitive it was almost insulting. I haven't found another mobile OS that comes anywhere near it yet. SailfishOS is the closest, but not quite there. BBOS10 is a vague nod towards gestures, but there are too many discontinuities. Android's a joke - I find a lot of the time hitting 'back' doesn't do at all what you'd think it would.