Well it depends. Brazil is certainly better now than in 2010 becuase their amazing youth crop (Neymar, Lucas Moara, Oscar) will be joining the more experienced former young guys who're still young but now have more top football under their wings (Pato, Marcelo, Hulk, Ramires, and David Luiz)
If there's 2 things that would concern me about being a Brazil fan it's Brazil's natural collapsing on the big stage that's seemed to happen lately. They're always one of the 3 favored teams to start the tournament and almost always fall short against an opponent. Their concerns are GK where they don't have a star and central defense. If they can hold those positions they'll be the favorites.
My personal favorites are the Klinsmann trained Germans. For my money, the Germans are only contested by the Spaniards for the best back 5. Neuer, Lahm, Hummels, Badstuber, Boateng, Schmelzer, Howerdes and the slow buy smart Mertesacker. Only weakness is their second full back which Boateng filled in fine before but Schmelzer may push him. The German midfield is the stuff dreams are made of though. Ozil, Schweinsteiger, Reus, Muller, the Benders, Podolski, Mario Gotze (who may be the most talented young midfielder in the world), Kroos, Schurrle and Khedira, you can build 2 world cup winning quality midfields with those guys. And they're great at striking as well with Gomez and Klose can be the off the bench killer.
Spain is also great, Iker, Ramos, Pique, Alba, and Albiol will likely be their back 5, I don't think Puyol will start much. Xavi and Xabi Alonso at holding midfield, Silva, Iniesta, Fabregas, Mata, and Carzola as the attacking midfielders (though I'm sure Busquets will find his way in there and move Xavi or Xavi Alonso up) and Villa and Torres for strikers. Spian wil lbe very formidable in WC2014, but I'd bet my money on the Germans because of their team currently being younger and having a speed and strength advantage.
Of course you can't count out the Portuguese, the Italians, the English, Russians, Dutch, Mexicans, and the Argentines. Any team that has Leo Messi is a threat. Especially coupled with Sergio Aguero and Gonzalo Higuin. Argentina's problem though is gonna be getting the balls to their super stars, I have serious questions about their midfield, and their defense and goal keeping are also suspicious. I think they'll run into the Germans or Spanish and get swept aside. But I personalyl hope for an Argentina/Brazil matchup cause that would be awesome. Probably end like 7-5