I recently got this cat trees/towers. This one, for my money, is the best by far. I have a large, 12 pound Ragdoll cat. She LOVES this thing. She sleeps for hours on the high perch and also will hang out in the little room. She spends several hours a day on this perfectly happy.
What I liked about this: easy to assemble, only took a few minutes, the base is large and sturdy and the tower won't tip over even when a big cat is on it, the wood edges are rounded and chamfered so neither the kitty nor I will get stabbed with pointy bits and the overall build quality is good. Both my cat and I are very happy. She even uses the sisal scratching posts. I recommend this one.