IF you have access to 30 or 50 amps of electricity all the time, then i would choose electric over propane. Especially if the electricity is free (like when you stay at a campground) In this case, i'd also use electric for heating the air inside the bus.
The problem is that if you wnat to park somewhere that doesn't have electricity, then 30 amps of 110 volt current is a lot of juice! Running a generator would be less than desireable, and unless you have a huge battery bank you can't run 3000 watts off of an inverter for very long.
Quis custodiet ipsos custodes (who will watch the watchmen?)