Well, there are different elements like break-building, defensive safety-game, attacking safety game, long-potting, shot choices between safety and break-building, cue action, mental approaches, physical condition and so on . But the way I think what is a good match player, is what players can produce when it going gets really tough, i.e deciding frames. Excellent example was Welsh Open match between Steve Davis vs Ali Carter, where Steve made deciding frame century with many most spectacular positional shots !! In the 90´s Stephen Hendry made 147 decider against O´Sullivan. Steve Davis is a one hell of a match player and so are John Higgins and Mark Selby the way I see this issue. I definetely voted Mark Selby since he has a well earned reputation being a deciding frame specialist.