Going into any World Cup, there are only four or five teams that are truly capable of winning it. Some outsiders may perform credibly, exceed expectations, or knock off one of the superpowers, but winning the whole thing is another matter entirely.
So, straight away, you can eliminate the vast majority of teams from consideration. This time around, I see only four real contenders (and it is the four favorites): Brazil, Argentina, Germany and Spain. Hence, finding a good bet is less about spotting hidden gems ignored by most punters, and more about finding a good price for a good team.
World Cup betting markets are too heavily influenced by form in the World Cup qualifiers. While qualifiers are a good way of assessing a team's general strengths and weaknesses, there's a huge difference between winning eight games over a period of roughly two years and winning seven games over the course of one month.
Some teams also have easier paths to qualification than others, which can make a team look much stronger than it is. This rules out fringe options like Belgium and Colombia: both teams qualified well but are relatively untested at the World Cup level, having failed to qualify for the last few tournaments.
On the flip side of this principle, France and England were probably a little too unimpressive in qualifying to warrant a wager.
In my opinion, the value is with Spain (7/1) and Germany (11/2). Both are good teams with good tournament pedigree, but they've been given slightly longer odds because they've both drawn tougher groups.
Brazil are worthy favorites, but you're not going to find much value for them at 10/3, particularly when some punters are attaching the sentimental and erroneous concept of 'home field advantage'.
Argentina (9/2) are worth looking at if you can find them at 5/1 or higher.
Finally, the Netherlands and Italy are worthy outsiders at 25/1 (again, tough groupings have seen their odds inflate), but don't bet the house.