I’ve a 16 km commute, with road, some steepish hills, and flowing (and often muddy) off-road. Been doing it for years, all weathers, with panniers and mudguards etc. My best solution (so far) is a rigid Al frame, with Gates belt drive and an Alfine hub. Zero transmision maintenance, except every 12 months for a hub relube. Before that, it was (in Winter), a chain clean, relube every couple of days. The belt drive is a tad slower, but if you want a commute bike to be utility, low maintenance thing, i can’t fault it – i won’t be going back to a chain for the commute. Best of luck !
PS i’m using a Cube Hyde. Mudguards,rack mounts,disk brakes..