Walking most important?....maybe try a dedicated SPD mtb/cyclocross/touring/spin shoe with rubber soles.Giro and Shimano offer many models of varying cost and tread aggressiveness.
Stiffness and power transmission* more important than walking?... just upgrade your pedals to road Spd-sl pedals like Shimano 105 or Ultegra level.
*Sorta...that’s not to say mtb shoes can’t be stiff.