It's not as easy as it seems!

I have two offers from the above mentioned universities. Edinburgh will start in September, Aberdeen in January.

But I can't start the LLM in Edinburgh in September 2009 because I'll be doing a traineeship in the European Parliament until the end of the year. However, I could possibly defer my entry date and start in September 2010.

Edinburg's Europa Institute is better than Aberdeen's Law School but I don't know whether I can spend the 9 months from January to September in a useful way.

What do you think is the best choice concerning a career in Brussels?

Is it worth the wait?

I think it's worth the wait. If I was you, I'd ask to defer the offer and wait until September 2010. Don't get me wrong, Aberdeen is a great place and I really expect to get an offer from them next year, but I'd much rather go to Edinburgh (form both personal and professional perspectives). Congratulations for you on the fact that you've got offers from these great universities.

I concur with Beicon. Definitely defer and wait for Edinburgh if you are really interested in EU Law. There are so many interesting EU related research projects going on right now under Prof Shaw it is a great time (and will be for years to come) to study at Edinburgh and get first hand knowledge of the realities of EU law and the effects of integrating so many countries!
Best of luck.
ps- Edinburgh is a far more beautiful and interesting to live, which is also important...especially in the dead of the Scottish winter! ;)