Depends on the situation and camera
I find the flip screen on the G1 and Canon Powershot very useful
I find the flip screen more useful that the standard "flat" LCD screen
on my DSLR I prefer the OVF, except when doing tripod work when the use of the LCD in preview and manual focus mode is very good, (useful)
and on the M8 I have no option - so it's OVF and scale focussing
So what I need, Herman, screen and viewfinder wise - is the functionality of the Nikon D300 in a
Leica M Body with a swivel Canon or Panasonic LCD screen - but I don't think Mr Leica will accommodate "anytime soon" as you "cross the pond" people say