My 2p worth...
Over the last 15 years, I've commuted on the following over the same sort of distance as the OP:
Yamaha FZR400RRSP
Suzuki SV650S
Suzuki GSX-R750W
Suzuki GSX-R1000K1
Suzuki GSX-R1000K8
The SV was the cheapest to run out of that lot. The GSXR750 the most expensive (mainly because I kept crashing it). The K8 is my current toy, so it gets used for a commute in the summer for fun, but never in the winter.
However, I bought a new Bandit 1250GT last September and have been using that since. Full Givi luggage (2x 35l panniers and 45l top box), hugger, taller screen, heated grips, handguards, touring Scotoiler, and lower fairings, £6700 on the road. Bargain.
Been tracking the running costs since new, and it's costing 16p per mile to run. That is petrol, tyres, and servicing, but not insurance as the company pays for that. Although, that's only 250 quid a year inc business use.
Using it for a weekly run up to York from Birmingham at the minute and can comfortably get a weeks gear and two laptops into the luggage. Excellent bike.