In my opinion it's Type-F
Because:
* It's bi-directional
* It's grounded and ungrounded plugs use the same socket
* It's already widespread
* Your fingers can't touch the live wire as you're plugging in a wire
* Low footprint
Furthermore, appliances compatible with Type F are almost always compatible with Type E as well, it’s just a matter of including both grounding mechanisms which they all do to avoid designing multiple cords.
I haven’t yet visited the UK so the only time I’ve had trouble plugging in something in Europe is in shudders Italy.
Ek-Hou-Van-Braai
azertyfun