It seems to me that the MH will be more liable to have issues simply because of the complexity. If you include "tow vehicle and trailer/5th wheel", then that might change the odds.
When we picked up our 5th wheel, the dealer had a campground where you could stay. The place was nearly full of MH waiting to be worked on. We talked to some and a couple had been there for a week or two, and one guy had to come back in a month or so because they were waiting on parts. It seemed that most of the issues were electric/electronic in origin. That's why I tend to lean towards the MH being the most likely to have problems.