High wing advantages :
No worry about prop clearance so props can be large/not close to the ground for rough field/gravel operations (what sold many of the F27s compared to the 748 in the 1960s-70s).
No wing spar through the cabin which you still get on smaller low-wing types like the Jetstream.
Same is true for jets, especially the clearance. Note the smaller types are either high wing (146 and Do328 jet), have to be rear engined (RJs and business jets) or have bizarre inefficient configurations (VFW614 with engines on top of the wing).