( if you were referring to me 25check )
I am only a pilot, and having used most of the airports mentioned, I merely give advice on my personal experience. I have no connection whatsoever to Signature or Luton airport, but have always been extremely satisfied with their service.
Location wise I would never choose anything other than City, however prices, and the fact that I am not allowed to fly in there - make that an impossibility.
Stansted is my second choice, for when I cant get into Luton.