I have 4 cats, and at least a dozen cat trees. I push 3 or 4 of them together to make a little kitty playground, and they love them. This one is great because of the different levels. If you put it next to a cat tree that is difficult to climb, the cats can use it to help access the other cat tree.
As for brands, I own mostly New Cat Condo cat trees. They're solidly made and come assembled. (I have one cat tree from Go Pet Club, and it was a nightmare to put together, plus one platform isn't attached because the screw holes were in the wrong place, so I just gave up on it.) But all my New Cat Condo cat trees are excellent.