Has to be 1974 for me. Some people may say 1970 but they are wrong. WRONG I SAY!! 
Main reasons I would say so are
1 - 74 was more competitive, The Italians were too knackered to put up much of a fight in 1970
2 - The crowd in the 74 Final were more lively
3 - Cruyff was in it
4 - Johan Cryuff is awesome
5 - 74 had the added drama of the penalties for the both sides opening goals
6 - You had the excellent battle of "Total Football" Vs "Gruff German Efficency"
7 - Did I mention Johan Cryuff?
What Final is your favourite?

Main reasons I would say so are
1 - 74 was more competitive, The Italians were too knackered to put up much of a fight in 1970
2 - The crowd in the 74 Final were more lively
3 - Cruyff was in it
4 - Johan Cryuff is awesome
5 - 74 had the added drama of the penalties for the both sides opening goals
6 - You had the excellent battle of "Total Football" Vs "Gruff German Efficency"
7 - Did I mention Johan Cryuff?
What Final is your favourite?