I think something like a flat blade 3 pins in a row italian style plug would be the ideal. Flat and square plugs tend to stay in place compared to round plugs and the 3 pins in a row would be space compact, while still providing grounding.
The reason for the UK triangle is that the orientation is set, so you know which of the supply wires is live and which is neutral - and if the plug is half removed the top exposed pin is ground so if anything fell down onto the socket it wouldn't touch a hot pin
Extreme I know - whoever designed the UK plug was obviously paranoid.
