IMO best value for your money are the Swiss. They are going to be playing home, and are VERY GOOD and upcoming young team. They qualified in tough group for the previous world cup, and did well at the worlds despite having very young team. I would wager for them to win their group and to win the whole thing as well.
Another value for your money is Sweden to win their group as their in the easiest group. Spain is overrated and SHOULDN'T have come out of their group in qualifying. Russia a medicore team. Greece is average team. This would be my lock to win their group at least.
I would STAY away from France, Netherlands & Italy. Not because their not good enough, but their in the toughest group. Atleast one of those won't be progressing, and possibly two. Romania is underrated and are very good team. I think they have as good of chance of coming out of the group as any of the other teams.
I'm looking forward to this as its better then world cup in the sense of competition. Where as world cup starts in 2nd round, euros with level of high competition starts RIGHT AWAY.