The OP should not put so much faith in "New" unit waranties. This and other Forum's are full of horror stories about what a joke most warranties are. Either the warranty is a joke or the dealer that sold the unit has zero interest in servicing it after the sale. God help you if you buy from one dealer and expect another to provide anything close to reasonable warranty service... as you are absolutely their lowest priority.
Also, most warranties are one year only with a few manufactureres offering 2 years. The other side of the coin is that when you buy used any major defect {they quickly become apparent} has been dealt with as well as the annoying little stuff that first owners get to chase down.
I would always look for a quality unit, lighty used and well maintained {with the appropriate documentation of all required service}. Most folks don't use a new unit all that much and few, having spent a large chunk of money, are abusive of their new investment.
When you buy a rental this is often not the case. Most rentals are trashed by ignorant {not bad people, just folks that just don't know any better/or have a clue} operators. Every Class C that has ever blasted by me on the interstate doing 80 - 85 has been a rental. The overwhelming number of rental operators have never even heard of the Tow Haul mode or have any clue as to its proper operation. Consequently many, if not most of these units, have had their transmissions {and brakes} severely abused {somewhere between repeatedly overheated and outright fried}
I make a point of chatting up rental operators often sharing a few tips and firewood and am always amazed at how little instruction they received from the rental company. :S Yes the rental companies refurbish and pretty up their coaches but they cannot get rid of them fast enough after just a couple of years and there are a number of very good reasons for that.
So many first time buyers buy the wrong RV creating a huge pool of potential bargains given their desire to get into the right coach regardless of the cost. In many states {Arizona being one} there is no sales tax on private party sales.
I am on my third RV, a near new Aliner, an as new Fleetwood TT and now our Nexus Class C that I found with just 6,205 miles on it after 18 months. In all three cases I saved a ton of money and all three were trouble free. When it came time to sell the first two I recovered nearly all of my original purchse price and am now nearly 50K happy camper miles down the road after 4.5+ years with our Nexus.
Lots of ways for a buyer to go... new, used, rental and no one way is perfect but a quality rig from a motivated private party has been the best path for me. Bought our Class C from a dealer as it was exactly what we wanted and eliminated any further foolish thoughts of buying new but I sure wish I could have met the original owners... now that would have been a deal!
As always.... opinions and YMMV.
:C