My wife and I bought a new 3600RS about 6 months ago. Had very minor issues (door lock broken, fantastic fan not working correctly, kitchen counter light fixture bulbs went out/defective) but they were fixed, no big deal. We have had no major issues and no other minor ones since and hopefully won't. We also researched many, many brands and chose the Blue Ridge (also seriously considered the Cedar Creek and Cardinal). So far, we have been happy with our choice.
Quality among RV manufacturers is generally questionable at best. They all have their issues and many times it is issues with the items all the manufacturers use in common (refrigerators, water heaters, pumps, AC units, etc.). I have owned 7 units over 20+ years and they all had their own set of issues. I either fixed them or moved on.
Research your potential dealer as well as the brand. A "bad" dealer can kill
any "good" brand due to poor customer service. A "good" dealer can more than make up for most short falls of a "bad" brand with excellent customer service and as long as the shortfalls they can't make up for are not a big deal, then you won't care.
In my humble opinion, all three brands you mentioned are good brands but understand, the Cardinal and Cedar Creek both are much more expensive brands than the Blue Ridge... you get what you pay for in RV's just as anything else.
Make the best choice you can for what you are looking for in all aspects... brand, dealer, money, and enjoy!