Hi,
It really depend on what you want to do.
Flexicam is officially supporting lenses up to 105mm. I used the CFE 120mm Zeiss with success via adapter.
I use 50, 80, 120mm CFE Zeiss (via adapter) and 35 and 100mm Digitar on Copal, the 72mm will follow soon for my Flexicam.
On a DSLR my standard, everyday lens would be a 35 or 50mm.
The day I win the lottery and retire i would probably just buy a nice ALPA with just a 55mm Rodenstock as a P&S for my documentary work. A bit wide angle, but not too much.
Tom-