I would love to see Poland win in May. It is in my top 5, although not my number 1. But a win for Poland would be so deserved! We would have a new country winning. And the song itself is quite far from what have won the contest before. It would surely rise the interest for the contest in Poland and hopefully in some of their neighbour countries as well.
I would love to see France winning as well. Another song in my top 10.
Other countries that I would love to see winning some day will need to do so with (much) better songs; Spain, Portugal, the Netherlands.
From the countries with a real chance of winning (I guess); I would say Hungary. It is not in my top 10, but can be with a good performance on the night. And I would love for Hungary to win; new country, non-block country...