In 
Premier League  between ( 
Manchester City  and 
Manchester United )

.... or
In 
Serie A  between (  
AC Milan   and  
Juventus  )

.... or
In 
La Liga  between (  
Real Madrid   and  
Barcelona  )

.... or
In  Bundesliga   between (  
Borussia Dortmund   and  Bayern Munich  )

.... or
In  
Ligue 1   between (   
Montpellier   and   Paris St Germain  )

Premier League of course no doubt! 2nd place: AC Milan vs Juventus, gonna be very interesting in April and May.

for me 
In 
Serie A  between (  AC Milan   and  Juventus  ) specially after last match 
then 
Premier League  between ( MAN city & MAN U ) 

Premier League between ( man & man ) for the champion .. and also between ( Arsenal and chelsea ) for 4_th  place

@Gennady  ..  yes , i think April and May will be a critical  months in 
Premier League and in 
Serie A

Real Madrid vs Barcelona will also be a exciting match :D

@Monica . yes ... 
( Arsenal , chelsea and Newcastle United  ) for 4_th place ....   will be an
exciting competition  

@
CR7skillz  ...  of course the match will be  
exciting  ,, but i think that real madrid .. is closer than barc. to the title !! .. what ever who will win in the match !!.. what do you think ??

@Mikool .. I hope Arsenal can  take the 4_th place .. good luck also with your team :)

Very difficult question. Since I'm french I watch most Ligue 1,with PSG and Montpellier,both amazing season.England is first,but Bundesliga and Serie A are following.

Lega Calcio for me,Juve only unbeaten side in Europe and Milan dont look to take foot of gas at moment,so is great to watch,but Mikool you forget Udinese they can suprise as Serie is fool of suprise Laliga fool gone conclusion,Germany is intresting and France eiiishhh,I hope humble Montpellier win PSG is only new owner and money,booooooh.Laliga no club apart from Barca will spoil Real title race they are just too minor to two SSpanish force.

I cannot say what is more exciting b/c they're all tight and anything can happen (except for La Liga). I will say that I am also pulling for Montpellier b/c I would like to see them rewarded b4 their stars are lured off. 

@Difensore , Yea Juventus is this is year pretty good... maybe its because they have pirlo cuz pirlo is the guy who controls the midfield at juve...

@Difensore ,  i  don't think that   
Udinese  has a chance .. only juve or milan ....... i think also  there is a great 
competition  between (  Inter , Napoli , Roma , lazioand & 
Udinese   ) .. what do you think !?!?

@expertfootball11 .....  from France but you live In Northen Ireland and you  support RM and Germany ... is there any team you didn't know ...hhhhhhhhhhhhhh .. i think you are special :D :D

@CR7skillz ,  pirlo of course a great player but  one man can't do every thing .... is Ronaldo ..do every thing .. or there is a team ... and a manger  ... same thing for us .....  am i right ?

@Footaholic .... 
except for La Liga ... 10 points ...  don't mean that real win it at all !!

@Mikool: it is may not yet be mathematically impossible, but come one... even Pep admitted RM all but wrapped it up. 
Perhaps Expertfootball is a cosmopolitan football fan... has a vested interest throughout Europe.

And you forgot in Portugal, between Benfica and FC Porto!

Man city and Manu takes 1st = I think that this will be really close.....Probably the next match up between the two the winner take all.
Milan and Juventus next = I think that Milan has the players needed to win this but Juventus plays really well together. I would go with Juventus in this one. (Not that I support either team)
Real Madrid and Barca = Madrid just has too big a lead Barca can't overturn it I don't think. If Barca beats Real in their match there might be some hope....If Madrid win it's all over.

@European , yes 
Benfica and FC Porto ..   sorry for forget this ... but you don't say ... Where is the most exciting competition until now ? .. !!