Hmmm, I'm going to make the assumption you're looking at a Jayco Designer since the Montana is one of Keystone's higher line 5-r's & you're trying to compare 5-r's that are on the same "playing field". My knee-jerk opinion is to go with the Jayco. Jayco has a fine reputation for building a quality 5-r. For me, if money is no object, I go for new with warranty instead of used. Although with new, you take a big depreciation hit that first year.
We owned a Keystone Cougar (mid-priced) & it was a good unit at a nice price. I would not hesitate to recommend Keystone.
It all depends on which 5-r suits your needs best & is a good match for your tow vehicle.
If you want to give us a little more info on the models you are considering, some of us might be able to provide more opinions on our experiences with those models.
Lori & Dave - FMA #3415 | FMCA #F419886 | RV/MH Hall of Fame Lifetime Member
2006 Fleetwood Bounder 36Z & 2014 Honda CRV AWD, My iRV2 Photo Albums
How is it one careless match can start a forest fire but it takes a whole box to start a campfire?