I certainly understand how quickly it starts to make you dizzy. We started looking again a couple of months ago and I had to push it aside for a bit.
Nobody makes a bad 5er, so you're off to a good start :). Until you get into custom builds, I don't think you will see a dimes worth of difference in quality - they all are less than great.
Take your favorite ones and site down inside, get a feel for the comfort and features, and it will come to you. If you are in cold areas, know the thickness of the walls and whether they are covered underneath. At the higher weights you listed (13K), you are probably going to want 7K axles.
Happy shopping.