@Pratt welcome (hopefully to the family)
GD is a pretty amazing manufacture. The only thing I can say is you will probably have a hard time finding someone here that is really disassified with the brand. Many of the owners, say prior to 2017 were really taking a chance on a brand new brand. You will find that most of them have had a rock solid product from day one.
As far as Jayco vs Grand Design – Jayco was just purchased by Thor Industries in 2016 but is still managed by the family that started the company. They have been known to be innovative manufacture over the years and as far as travel trailers go have been known to be one of the leaders in the industry.
Grand Design has a similar story with them being purchased by Winnebago but still being independently managed subsidiary. Winnebago manufactures most of the parts for their motorhome line. We are talking molded parts such as tanks and wheel wells as well as curtains, upholstery and bedding. This sets Winnebago apart in that they can make not only custom pieces for their own needs but set their own quality and let that be differentiator in the market. Jayco like almost all RV manufacturers gets all these pieces from the same generic OEM suppliers. This is why there is not much innovation in the market when you are all working from the same basic pieces.
For me it has been the customer service. I can tell you that I have a trailer right now that I would consider a lemon. The kitchen slide, completely detached from the sidewall over Memorial Day weekend. The service team at GD, first gave me his personal cell phone number to call 24x7 all weekend. He offered three solutions, a way for me to temporarily fix the issue. A mobile service guy, who none could be found. Finally he call all the local dealers around and got one to get a team to help me get the slide attached in a few hours. What more can you ask for then to have people know you are in a pinch and over a holiday weekend to keep in-contact to make sure you were taken care of.
I have other major issues with my specific trailer due to this incident and they are in the process of picking up the trailer and driving it back out to the factory to be rebuilt. No questions, no fuss a slight inconvenience but they want to solve it right.
I will let someone else speak to the PDI process which is another standout difference for GD trailers.