We used a portable generator when we camped with our travel trailer and it did everything we needed it for. When we went to a toy hauler I was looking for one without a genny because I "didn't need no stinkin' built in generator". The length we wanted all had Onans. We don't use it that often but it's so nice to roll out of bed on a cold desert morning, hit the starter button and within minutes have coffee perking. I'm so glad I don't have to fight a portable or multiple generators. Resale might be another consideration. It may be hard to sell the trailer without a built in generator... In my opinion..