I would be curious to see what are the exact benefits of all options.
However, I firmly believe we should join a site that has already proven its worth. I'm thinking about Chess.com, ICC or Premium Chess. There is a lot of advantages in joining Premium Chess, since it is owned by FIDE, but we also all know how FIDE likes to take the biggest cut... So, a deeper financial analysis is probably required.
One major issue from Premium Chess though is that our rating appears on the FIDE website... Given how bad I am at blitz, I wouldn't quite want that to happen...
As far as Chess Supersite goes, I like that they include a lot of different options. However, the website is very amateurish and the interface very poor. I understand this is a beta, but one thing I learned is that such design flaws usually hide a lot of worse problems under the hood. And I honestly wouldn't take the chance there.