While I don't have the 365, I did purchase a new 2015 San Antonio last February, so some of the workmanship and fit and finish issues that affected my rig could certainly replicate themselves in the 365 I would imagine. So here we go...
Both recliners had cracked backs and had to be replaced (someone had attempted a cheap repair on one of them prior to selling it to us)
Dinette slide topper shed no water and looked loose (was missing 2 screws),
Driver side front landing gear had to be replaced due to leaking seals
Norcold 1210 fridge cooling unit completely failed after 4 months
Carpet was fraying on edges of office slide
Office slide was misaligned and leaving gouges in the carpet. Had to be removed and realigned.
Wall paper by dinette (around external TV box) bubbled badly after about 6 months.
Multiple galley water leaks into underbelly (connections, not the tank) - this was a major pain!!
Multiple water line leaks in Pex lines behind UDC
Back splash behind sink (cheap cardboard) fell off. I replaced it with something better.
Loose sink fixtures
Microwave (and the cabinet it is mounted to) are not installed level, causing turntable to come off its track all the time. I need to shim this.
Coffered ceiling came loose after one trip and had to re-secured.
Water was getting into underbelly during travel in even light rain -soaking the insulation.
There were a few other minor nuisances we had corrected on the spot at our PDI. Most of these other things happened on our first few trips. Needless to say, I was very disappointed in initial quality and workmanship. I had owned 2 previous fivers of another brand (world's best selling fifth wheel, or so they say) and had become disappointed with their quality, particularly multiple tank leaks and terrible external graphics that made our rig look like a FEMA trailer after only 2 years. Electrical and landing gear issues too. However, when I compared their top model with the Landmark, side by side, the Landmark fit and finish looked much better. It seemed there was more attention to detail on the surface, which I hoped meant the same throughout the coach. In addition, I felt the Landmark had more options for the money and was a beautiful rig on the outside. Having owned 5 RVs, I knew we would have problems with the third party supplied parts (fridge, H2O heater, furnace, etc.) But, I really liked what I saw on this forum as far as owner participation and company engagement - that was a big plus. I was ready for a change so I took a chance. Overall, I'd call it a push. No way of knowing what type of problems I'd have if I bought the Big Sky, but I can read their forum and see there are plenty of problems there too.
However, as has been said a million times, the dealer can make all the difference. My experience with my dealer's service department was TERRIBLE! At least 5 trips (350 mile round trip) to try and get things fixed. They could never get things fixed the first time (and sometimes not the second). Post repair Quality Control was non-existent (belly not secured properly, basement doors left unscrewed, missed items). It took a formal letter to the manager, multiple phone calls and e-mails, and apparently, a housecleaning in their service department, to get things fixed right. Finally, last month, after 11 frustrating months of ownership and multiple ruined trips, we have everything (knock on wood) repaired. All was covered under warranty thankfully.
Bottom line - would I buy a Landmark again. Probably. It is a beautiful rig; as well built as others in the same price range, and has (other than my dealer) great customer service and support. However, don't expect that it will be vastly superior to other brands. Face it - the components are all made by the same folks putting parts in Montanas, Forest Rivers, and Jaycos, et al. A Norcold can fail in a low end TT just as well as a 125,000 5er. Lippert parts are Lippert parts. And so on. But if you can, research your dealer's service reputation. It's a guarantee you will need service from a Heartland authorized repair place. Find a good one!!
Good luck!