There are times that a MH would be more convenient. Being ably to use the little room without getting out, can put a crock pot in the sink and fire up the genny and have dinner ready when you want.
Other than the cost of the MH I opt for the 5er. I only have one drive train to take care of. When I get where I am going I unhook the 5er and have my touring vehicle already. I think you do get more room in the same length from a 5er The choice must be yours. Good Luck in your search and Happy Camping.