This may seem like an unusual one, but I'm a big fan of Tartakower. After playing through his book, "My Best Games of Chess 1905-1954," I realized how good of a player he actually was. If you covered up the player names of any of his early games, you'd actually believe they were played by Morphy (no higher compliment IMO). Later, he became more positional, but still just "did stuff" until he could get around to a kingside attack. Still later, he became more truly positional, playing soundly until he could find a tactic to turn things to his advantage or win in the endgame.
The interesting thing about this many-sided progression is that at any given tournament, he might play a rock-solid QGD, or the Orangutan; he could play a manly, straight-up "develop and kingside attack" that looks like it was played in the 1800's, a wild tactical slugfest ala Tal, or a game that looks like Capablanca played it. I can't think of many players with such a range.
His endgame was strong (Rubinstein referred to him as one of the 3 best endgame players in the world at one point), he often broke away from known openings and played his own game, he aimed for interesting positions, and never shied away from fight. He also had that spark of genius that allowed him now and then to find those weird, completely unexpected moves that turn the game around.
Who is it? (Mine is Carlsen)