Welcome to JOF, we hope you stick around and ask lots of questions.
Yes, Jayco has a great warranty, but that depends a little bit on how good your dealer is as well. Jayco stands behind their product, but many dealers do so much volume that warranty repairs can take a long while. But if you are a new owner, having the backing of the dealer and their experienced techs can be a good thing to have.
I don't really regret buying our first trailer new, but now I understand why used can sometimes be better. A trailer has a lot of different systems; it is a little house on wheels. Often there are initial build issues with a one or more systems that take some time to work out through your dealer. These trailers are built a bit more like houses than like automobiles - the assembly line is NOT a precision line.
So my advice with a brand new trailer is to go in with an expectation that there may be a more than a couple of visits to dealer in the first couple of years, and that those visits may take some time to get things resolved. Just be comfortable that everything will be taken care of, and once everything gets dialled in, you'll be camping regularly.
I never returned to my dealer after the first couple of years; by then the number of issues dropped dramatically, and what did come up I was comfortable taking care of myself. Now that we are comfortable with all the systems on a trailer, we were very comfortable buying our second unit used and diving right into doing all the maintenance ourselves. The first owner did a great job of taking care of any initial quality issues and maintained it well, so our used experience has been great.
2011 Jayco X19H (purchased 2015)
2008 Jayco 1007 PUP (purchased new, traded for the X19)
2018 Nissan Titan Midnight Ed.