Comparison, OK, pretty general but here it goes. Keep in mind I'm not knocking Jayco. I think they build a great product. It's just that we found something we liked better. First this forum, even though not directly affiliated with Jayco, is alot more like family. The Forest River forum has so many threads for their individual brands, it just seems more fragmented. There are some informative and helpful posts though.
We had the Jayco 351RLTS on our shortlist so I'll use that for comparison to our '13 Sabre 34REQS-6. Jayco comes standard with a 2 year warranty which I never had to use on our "08 Eagle TT. Forest River offers the 2nd year for $150 which IMO is a no brainer so I got it. The fit and finish were great in both Sabre and the Jayco. Cabinet/drawer construction is equally good quality. Dometic fridge in the Sabre instead of Norcold in Jayco. Fireplace in the Jayco had the 'stone' surround which made it look more like a fireplace. Our fireplace doesn't have a 'stone' surround which allows for more lower cabinet space. Sabre's come standard with a Toshiba TV, we upgraded to a 40". Don't know what Jayco is using now but I wasn't too thrilled with the RCA that came with our '08. True 5.1 surround in our Sabre living area w/ 2 bedroom and exterior speakers. We like the U shaped kitchen in the Sabre instead of the Jayco L shaped kitchen (a biggie for DW). Jayco dealer never mentioned a floating island option which might have made a difference. We both like the 1 door bathroom in our Sabre. I'm an early riser while DW likes to sleep in. She didn't like the 2nd door from the bath to bedroom. Furniture quality and construction on both are equal. DW likes the wood floor look on the Sabre. Carpet and pad quality seemed equal in both. I still haven't figured out why but believe it or not our Sabre has 40 interior lights (overkill IMHO) either in the ceiling or under the cabinets. There's even a light in the shower, which is 30" X 50". Lav sink and countertop is bigger in the Sabre. Both have hi-rise porcelin throne. Our converter/fuse panel is in the curb side garage, PITA. I think it's more convenient if it was located inside the unit but during PDI tech guy said its because people complained about the fan noise. I still like the L shaped sofa in the Jayco, but oh well. Sabre had an exterior paint option which we got. We got the thermopane windows which were also available on the Jayco. That's about all I can think of right now. Any specific questions I'll try to answer.