If the bike will be parked on a parking with lots of bikes piled up, I'd avoid disk brakes - disks could get bent more easily than the wheels accidentally.

For convenience, I'd also avoid any suspension - adds weight, price and doesn't make much (positive) difference for pavement riding.

The most important thing - mudguards. For me at least, they offer a great deal of comfort for commuting - even when it's not raining, riding on a wet pavement without them gets you quite dirty often. Mudguards allow me to ride to work in the jeans I work in, no need for a change of clothes - saves time and hassle. Same for grocery shopping, going to town (cinema etc).

On the other hand, going off road, mudguards can be dangerous - a branch can easily get stuck between a wheel and a mudguard, causing an unexpected crash.

So I'd get a cheap, no suspension, bike for commuting (prefer 28" wheels bikes, though 26" has it's advantages) and another bike for "mountain biking".