I say Argentina just because I was in Buenos Aires recently and the people there are really into it.
You're right there....those South Americans generally are absolutely nuts about the sport.
I seem to recall a Columbian football player respoinsible for conceding an important world cup goal being shot dead as he exited the plane home a good few years back.
And of course....I think it was El Salvador and Honduras (perhaps some Egghead can put me right if I've gone slightly awry with the facts there) who went to war over a football match...yes THEY STARTED A WAR BECAUSE OF A GAME OF FOOTBALL
Regretfully I cannot bring myself to wish any team featuring Maradona any luck whatsoever because he's a filthy cheating scumbag....
And that's quite sad because I think Messi is an absolute gem of a player