We bought used twice, a 1990 HitchHiker 34.5 fiver in 1997, and a 1998 two year old Challenger 36 footer in 2000. No comparison. The older HitchHiker was abetter unit seven years old than the two year old, never used Challenger.
The best units do weigh more, so plan accordingly. Getting the best trailer and too little truck is as bad, and because of safety issues, can be worse, than having a junk trailer!
But buying used presents its own set of challenges. Can you evaluate the condition of a used rig? Do you know how to check for signs of leaks or frame problems? Know how to pull the wheels and brakes? Check the furnace? etc?
However. As said so well already, even a major goof on a qulity used purchase can be fixed for a few thousand at most. You lose four or five times that when you drive off the lot with a new one.
Stay with the ones that are the usual suspects vis a vis quality.
HitchHiker (Not HHII)
and a few others.
I would never buy new. I can always change the drapes, blinds, countertops, furniture, etc. And make it my own, as I did with my custom mods on both my fivers.
But others who buy new are alright for them too! If you don't mind swapping a bit of labor for the lower price, used makes sense.
If you never modify anything you buy, or work on them, new may seem the way to go. But as so well said, you still end up a year later with an entry level unit with no warranty.
You can replace any floor covering reasonably yourself including the vinyl. You can change the furniture, TVs, appliances, etc.
So you can much cheaper make it better than new, as with a little skill, or help from your friends, you can make it trick, not just OEM.
Just look at Ken Lenger's pages or some of the others here.
I am not advocating starting with a junker and doing everything by any means. But one or two changes are reasonable. I usually have 10% at least of the purchase price reserved for unexpected repairs or expenses, for my used purchases. Be that a house, a used car, or an RV. No one can catch everything, just come close.
One more thing. The brands I listed work with their second hand owners as well as their warranty owners. And much cheaper than going to a dealer for repairs, with the work done right the first time.
RVs are mobile right? Make a factory trip! More fun with the good brands than you cn imagine!
Too many times the cheaper brands do not have factory repair centers, a must for me, new or used. Or they won't ship parts direct to the owners. The ones I listed do.
Decide which you are. Lose it up front, or spend a bit to make it your own. Gawd, if I bought new I'd have the initial loss, AND my mods as costs to boot!