Except for the diehard Chevy fans, the V10 is the prefered engine for MH chassis use. The new models are much better than the earlier years. GM even thought of coming out with a V10 but the last I heard they killed the project.
As for diesel, I am a fan, but right now the cost of diesel is too high to give any gains from higher mpg. The Class C MH chassis do not have room for intercoolers and so the diesels are not as efficient as the ones in the pickups. Some Class A models may be different, but it looks like the payback for the diesel is almost non-existent.