If you want high reliable and low maintenance, go for enclosed parts. So rollerbrakes, interal hub gears, enclosed chains and sprockets.

My communter bike has shimano roller brakes, 3 speed shimano nexus internal hub gears, enclosed sprockets and chain. Also close fitting mudguards, bolted on led front and back lights, cargo carrier and bungees, puncture resistant tires and ofcorse a bell. All mounted on a heavy duty frame. Requires very little maintenance and keeps you clean.