I've had one house with hardwood floors and a linoleum kitchen and now have wall to wall, with Pergo in one room and Porcelain tile in the kitchen. Both houses held a couple of humans, a couple of cats and one small dog. The cat hair is worse, of course on the hard surface floors, and you can track dust and whatnot around on your cold little feetsies, which is a drag when you carry that dust or dirt onto the carpeted areas (my carpet is a very light cream color). Hardwood does scratch, and water stain, but it's very nice. To keep it nice is a bit of a pain. Maybe the newer ones are easier - mine was an older home. It took a lot of dust mopping and mopping in general, and the traffic areas did look worn easily, just like with carpet.
I have a bit of trouble with the Pergo looking filmy after washing and is it LOUD! I dropped a fork on it and everyone practically jumped out of their skin! But it doesn't scratch. You still have cat hair and dust though.
I don't think you mentioned tile, but it is also nice. Boy you had better not drop a glass or a plate though. They explode! My tile is fairly easy to clean, but it has a bit of a rough surface and I go through mop heads regularly. Linoleum (or whatever they call it now - "No Wax" I think) is icky.
Carpet is soft and quiet and warm, but you have to vacuum a lot. Of course, spills are a bigger problem than on your hard surface floors, but if you are diligent, you can keep them at bay as well. Generally, I've been happy with carpet as long as I keep it clean.
My expert opinion - get what you want to have in the house, but realize that you have to clean it OFTEN, and none of these surfaces are the easiest to clean properly.
BC