We have a '14 Montana High Country which for all intents has been trouble free. But with that said, sure there have been a few niggling problems but nothing yet that would make it a negative experience in about 15,000 towed miles. Could Keystone have done better in a few places - sure. It probably should have had 6000 pound axles - but it is in the 5200 pound spec. Should it have had better tires? For sure, but many 6 figure RVs have the same junk Blow Max Bombs. Could Keystone have done a better job with the carpeting - probably, though it is surviving and is probably the same as those noted 6 figure 5ers.
Get what suits you. No matter what brand you choose, there is always the RV that seems to have everything that could go wrong saved up for that particular unit - or vice versa and get the best though most RVs are in the high end of the middle - a few problems, but no big deal