Because of the vast number of varying rotating formats and card pools available to those formats the answer to that question can be very difficult to answer. Any deck can be shut down by another deck...
There really is no "BEST" card. If one card must be picked, then it is the "Black Lotus" card (which is banned in most tournaments).Black Lotus is one of many cards that are banned from...
Andre Coimbra is the current World Champion having won the 2009 World ChampionshipsThere have been 23 Hall of Fame Inductees that have some sort of positive influence on the Magic: The Gathering...
It depends on what you want from your Planeswalker. In the current environment, based on monetary cost and popularity, Jace The Mind Sculptor, Gideon Jura and Elspeth are the "best" Planeswalkers.
This question is very subjective. it comes down to what you play and what you like to play and what you are comfortable with.AFAIK "Keeper" has never won a major tournament, best placing that I can...