Fuels can be a pain. I've got a PE-75 from 1946 that doesn't take too well to the ethanol in modern gasoline. I'm trying to find a reliable source of unadulterated fuel.
Generally speaking, diesel is a great fuel for generators, but it's a significant outlay in initial cost. A 6000W diesel costs about the same as a 12000W gasoline, both portable.
Being in the Greater New York Megalopolis (starts somewhere around Hartford, CT, ends somewhere around Princeton or Trenton, NJ) there's nobody around here that doesn't either have natural gas or LP delivery. It makes tri-fuel generators a popular item at my shop. LP, NG, and gasoline with little hassle switching. Backup your house or go camping with it. Have your cake and eat it too.