My current commuter in wet-winter-darkness mode*:
Genesis Day One Disc frame (a prototype, bought off the 'bay) with XT wheels and hydraulic discs. XT chainset. 42x16 and 28mm tyres giving a 70-inch gear. The clearance between rotor and fork blade was too close on the original prototype fork it came with (about 1mm and occasionally the two would rub when the fork flexed under heavy braking
) so I have retrofitted a Planet X cheapo fork. Blackburn disc-specific rack and SKS guards both fit fine; no bodging required.
Singlespeed. I can't be bothered to learn a whole new set of skills at my age!
*Which it runs pretty much all year, TBH.