Here is where I'm coming from when I say this;
My parents owned an Allegro - I worked on that a LOT. They bought it based on my recommendation. I fell for the hype of how great their customer service is, and theirs too made the trip back to Red Bay. Unfortunately the fixes didn't last the trip home, I ended up fixing it - and that was just the beginning.
Friends owned a Winnie - I worked on that a LOT - just a terrible roof design, even though it is "fiberglass". Our first MH was an Itasca (Winnie twin) that did not use the terrible roof design they use today.
We've owned 3 Newmars - if we ever buy again it will be another Newmar. I have spent far more hours working on other peoples stuff than my own, by a long shot.
Of the 3 listed, only Newmar does not use laminate construction. If it's laminated it can, and someday probably will, delaminate.
Many (most?) people post giving an opinion because thats what they own and they know about theirs, and thats fair. My suggestion comes from not only knowing our own but working on others as well. I currently have a 5th wheel in my garage getting a new roof. I am not an RV Tech, I'm a guy with a big enough garage to get them in and enjoy working on them - to a point.
For my $$$ I'll stick with Newmar.