Probably an MTB-based bike with mudguards (fitted with decent clearance), Marathon Plus tyres, flat bars and some sort of gearing. Flat bars are better in traffic, even if they're a PITA into headwinds, and braking options are wider. I would avoid derailleur gears on an everyday bike if at all possible, since the time taken declagging them on wet, dark weekends is too much to comtemplate. Fixed is good if you live in a flattish place or don't have to carry much. Otherwise, an efficient hub gear. The extra pound or two is a worthwhile trade-off for lower maintenance.
My commuting bike is like this. In 2012 I rode the Dunwich Dynamo without doing anything at all to it apart from topping up the tyres (it was pretty mucky, having not been cleaned since Easter), and did the fastest time I've ever managed. I wouldn't race on it and it doesn't have a rack (I use a courier bag) but it will always get there in a reasonable time. You wouldn't believe how little maintenance it demands; a chain or two per year, some oil and some air. A rear sprocket every two years and a very occasional grease of the V-brake pivots with a new cable. The brake pads have been on there since forever and the front rim is ceramic. I overhauled the rear hub (3-speed + coaster) last year and wished I hadn't bothered; it was still clean inside after three years.
If your "everything" leans more towards long rides in hilly country and luggage, you probably want a touring bike. They can handle horribly though* and they are not low-maintenance at all.
*my old Thorn Nomad was a horrible floppy thing when unladen but was surprisingly well-behaved with a load of stuff on the back. My current Hewitt Cheviot is fine unladen but it's impossible to ride out of the saddle when it's loaded with camping gear. Although I hated the handling of the Thorn at the time, with hindsight they actually got it right as a *touring* bike. The 26" wheels were annoying, though, as there was little choice of fast tyres.
