I don't have a preference between the 2 - I am British but also Catholic so confusing !
I always just go for whichever club has the players I like at the time.
There aren't really any players that excite me in the Rangers side (like Gazza, Albertz or Laudrup) so Celtic will get the nod for Samaras and Nakamura.
Where do your loyalties lie or do you not give a $h!t ?