I have a tendency to taking sides at every sporting contest I watch, so I naturally pick clubs to "support" everywhere, but it doesn't mean I actually have any sentiments towards them - often the choice is made for peculiar reasons (like a beautiful uniform, a specific player, and so on) and they change over time.
In Spain, I say I like Deportivo La Coruña cause a part of my family comes from Galicia. In truth, I hardly ever watch them... I much prefer watching Barcelona (in the late 90s and early 00s, I loved watching Real Madrid).
In Italy, I've changed sides a few times. Right now my favorite side is Napoli because Rafa is there.
In Germany, I always preferred Schalke for some reason, but I also quite like Dortmund, even though they're bitter rivals and hate each other
My favorite Scottish side is Hibernian. The Celtic/Rangers divide is boring - Hibs offer a more likeable alternative.
Not a big follower of French football, don't think I've picked any sides there. Never liked Lyon though.
I like Feyenoord in Holland, mostly due to Dirk Kuyt. I also got their shirt which I think is awesome.