mysterio, "top dog" is relative to how you judge such things. You do not count points, some do. You could view the Ghost-Ratings which is an Elo based system. If you wish to look at winning ratios, you could look at a players profile; however, that winning ratio includes games still being played. In other words, if a player is only playing one game currently, then the ration is mostly accurate, but if a player is in 20 games currently, then the ratio is far less accurate.
One other thing to note, every person plays for his own reasons, so even if you find your "top dog", he may or may not be the "best" player.