chess has no dice. it's just skill.
a few factors have to come into play, for someone to be the best.
over the years, the best players are widely considered to be bobby fischer, gary kasparov, and magnus carlsen.
without argue, if you put all three together in their prime, magnus will win. it would be such an epic battle. but magnus was influenced by fischer and kasparov and would ultimately have the upper hand.
magnus is the best ever. and fischer and kasparov are an important part of him and the history and chess.
the few factors needed are:
visualisation.. firstly you gotta be able to imagine the board and the pieces moving in your mind. you need to breathe the chess, to be able to comfortably play blindfolded.
branched-futures.. this is calculation.. when they say you gotta look 4 moves ahead, it is an exponential rather than a linear 4 steps. each step has branches.. 4 moves ahead is a tree. you gotta be able to see these trees, where the game can branch. and then each branch can have branches. this is chess skill and comes with devotion and practice.
memory.. the better you can remember, not just your own past games, but the games of others, the better you will play. magnus carlsen has a photographic memory of all the games like this. this factor is ultimately why he is the best. as well as:
practice.. this is where we see the new-school coming in. able to play hundreds of games per day, people have the internet. this is new, relatively. magnus was just in time to be able to do well in the computer chess, but the new generations are showing their skill in this factor. it reminds me of when the internet poker boom happened. a whole new group of talent emerged.
creativity.. the ability to evaluate the position.. to find the best move.. to combine attack, defense, combinations, pinning, skewering, and all the other tricks and traps possible.
chess is the best.