We live in a top floor flat and barely hear anything from the people below. Sometimes we hear the woman below us talking on the phone but she's old and probably got bad hearing so she probably shouts down the phone rather than talk.
It seems though that we are more likely to get mold problems because the guttering is up by our flat and probably more prone to leaks from the roof but we've had none yet (touch wood it stays that way).
I had a top floor flat & I loved it. No noise from below and felt very safe. I was the only flat on the floor though!
Only downside is lugging shopping up and down.