I believe you can use a superlative if you have third party (independent) confirmation. At least *someplace* I've read about recently has declared Google to be the best place on earth to work. Can't remember where, but I know I saw it somewhere.
Thanks very much for the benefit of the doubt. :)
Actually, though, the ad text is not appropriate for a couple of reasons - and it'll be tracked down and deleted before too long.
AWA