Cats rub your leg when they want affection, not when they're horny. Cats use a litter box. Dogs use your leg. In 1996, over 10,000 US deaths were attributed to a dog owner's choking on saliva during morning wake-up licks.
Cats always land on their feet.
Dogs just won't let you throw them. Cats let you kick them when you're stressed out. Cats will wait until you've read your morning paper before tearing it to shreds. Cats look cute sleeping on the t.v. Dogs just crash right in front of the screen.