1. Mercedes S Class, (sadly the second and third are going to pain me but...) 2. BMW 7, 3. Lexus LS, 4. Maserati Quattroporte (cramped and unreliable) and 5. Volvo (the Volvo is far smaller than all the others and while being supremely comfortable it is at least a class and half down market from the others listed).
The Maserati is certainly the most expensive and luxurious. "Better" is a very ambiguous term. You need to define what you mean by it before we can tell you which is the better at something.