Personally I find the disc brakes on my mtb a pain in the ***, even though the extra strong stopping power can be nice to have. They may in general need less maintenance, but when they do it's a messy, finicky job in tight quarters. The v-brakes on my commuter I can disassemble completely, clean, lube and put together again while listening to the radio and planning tomorrows dinner. And if they squeal or rub I know what to do about it. On the other hand, that may be just because I lack experience doing disc brakes.