(Technically a B-side if you pretend that the Smile [Chile Only] single counts!)
I would say LWTSH but when you consider they pulled it apart and used it to make other songs, e.g. the Fly and Ultra Violet (please bring that back), I'm thinking one of the other ones lol...gonna have to decide somehow.
Lady would be amazing and I think it would work very well with No Line on the Horizon (the song), but I'd rather hear Ultra Violet in that spot (or any spot, for that matter). Let's just say it would be the next best thing. I also like Luminous Times a lot, but I'll go with Lady.