Which clubs will win Europe's league titles this season?

With the new European club football campaign upon us, it’s time to look into the future and predict what the new season will bring.
Can last season's champions maintain their momentum? Who will be the key players, and what will be the main stories of the 2012-13 campaign?

Here are my picks for the continent’s top five leagues; have your say in the comments box below.
Spanish La Liga
Champions: Real Madrid. They are the finished article and as they enter their third season under Jose Mourinho I believe they have become even stronger than last season. There has been a shift in the balance of power and I think Los Blancos will hold onto their top spot this year. Led by Cristiano Ronaldo, they have all the weapons necessary to shoot down Barcelona once again.
As far as the Catalans are concerned, I think they will fall short. I am not convinced Tito Vilanova can easily step into Pep Guardiola’s shoes and have the same influence as his mentor did on the team. Most of Barca’s players have won it all, and I don’t think Vilanova is the right man to motivate them right now. Then again, when you have Leo Messi, anything is possible, right?
Top 4: Real Madrid, Barcelona, Atletico Madrid, Valencia.
Story to follow: Ronaldo vs. Messi. Last season, they scored a combined 96 goals in La Liga. Messi, who finished the campaign with 50, outscored 15 teams on his own. The question this year is what can these two extra-terrestrials do for an encore? I will be watching closely.