You don't want the expensive stuff if reliability is of prime importance. You want a 3 speed hub gearbox and a cro moly steel frame. Or in areas where servicing a real bicycle is hard to find, a mid range 1x8 derailluer system with bog standard rim brakes. It's not big box cheap, but the former have been being made for a century and are almost identical. New is about €200-500

In places with a decent bicycling culture you can get one second hand for a hundred euros or so.