Hiddink, with Scolari and Arena close behind. I don't think South Korea's next coach is going to have them playing anywhere near as well as they did under Hiddink. Scolari completely shook up the Brazilian lineup, abandoning the 4-4-2 in favor of three central defenders to take advantage of the strengths of Roberto Carlos and Cafu. It's almost unthinkable - a Brazilian coach adjusting his game plan to maximize his players' strengths, as opposed to simply looking good! It won them a World Cup. Arena led possibly the most tactically flexible team at the World Cup, playing 5 different starting lineups and 4 different formations in 5 matches and using 19 of the players on his 23-man roster. His team demonstrated that it could hold its own playing o jogo bonito, catenaccio, or anything in between. And there are few coaches who are as good as Arena at man management.
If we're talking how good the managers are then it is Erikson or (even better) Trapattoni. If we're talking about what they have achieved as National manager then Scolari's record is pretty good.