RE: Best Cards and how to counter them SF?
At the moment there are too many cards in SF and no deck has risen to the top. You can go check all of the threads asking for what is on top if you want to know the current metagame. I authored a thread a while ago that should clarify.
As for counters there are too many different decks to counter them all. However if you are willing to tech in 1-2 Unown G you should be able to shut down some of the more important decks.