With a new MH or towable, you are GOING to have issues that need to be addressed. RV's, even the best ones, always seem to have minor problems that need to be corrected.
With a used MH or towable, you will be getting it after the previous owner has handled those initial headaches. However, you need to worry about the care and attention that the previous owner gave it, and there is probably no longer a warranty. For instance, was the generator properly exercised every month? Was the plumbing properly winterized before freezing temps. Were the seams inspected and resealed on a timely basis to prevent water intrusion? This is not an all inclusive list.