You should check places like Flickr and find LF images you like and look at the FL. When I shoot medium format I love most my Hasselblad 903SWC (38mm f4.5). With my DSLR, I'm usually going for the widest end shooting my 17-40F4L. Naturally, I find my self reaching for my SA 75mm f5.6 when shooting 4x5. But that's *my* preference. You need to figure out yours.