Ground floor... It's great for the dogs, but I now live in a building that has become INFESTED with couples and a kid hogging all the one bedrooms and they park their nasty ass stinky feces and barf laden expensive strollers in the lobby right outside our door. It's like a parking valet for strollers. The building used to be filled with interesting fun single people, but no more.
The highest floor I ever lived on was in a tenement on the 4th floor, but was really just three flights up. I would LOVE to live in a highrise one day, but that will never happen i'm sure. But because I'm a dog person, I think ground floor is usually the best.