I'm gonna wait on the groups to form but let's see
On paper the top 5 favourites are Germany, France, Spain, Argentina and Brazil. The three European teams seem stronger and more deep so they have the edge. Belgium also has a very interesting team and has an outside chance while there are some nice teams yet with almost zero chances of winning but some chances of going to the last 4 if the draw is favourable enough and they avoid most of the big teams. Colombia, Uruguay, Mexico, Portugal, Croatia, Poland and even England come to mind. It's something that's been happening since 1994 at least. 94: Sweden/Bulgaria, 98: Croatia. 2002: Turkey/Korea(corrupt though). 2006: Portugal to an extent (could argue they were 7th favorites, dont remember the odds now, but Germany, France, Italy, Brazil, Argentina and the Netherlands were probably considered better. 2010: Uruguay, 2014: arguably the Netherlands.
I'm expecting Serbia, Russia and one of the three northern African teams (Egypt, Morocco, Tunisia) to do better than expected. That basically means last 16 for Serbia and the N. African team and last 8 for Russia.
But without the draw and the finalized rosters it's too hard to speculate.