Interesting to see the responses. I've never owned a Jayco and only owned 1 KZ, a 5th wheel.
Had absolutely none, nada, zero problems with the KZ...I did have a Norcold fridge that stopped working 2.5 years after the purchase (i.e. out of warranty). After getting the run-around from Norcold (I was just trying to find out who would be a good installing dealer, I was prepared to pay for it myself, but Norcold wouldn't respond to me), I asked KZ to intervene.
Within 1 day of contacting KZ, they called, asked me to confirm the model of fridge, and proposed an appointment time with a local dealer. I dropped the trailer off, came back a week later (they were done 2 days later) and asked what the bill was...$0. I pushed back (assuming I should pay for either the new fridge or the installation labor), still nothing. KZ had apparently taken care of everything.
Don't know if that's the usual practice, but it's my experience. Everything else being equal, or even if its not equal, I'd recommend KZ.