I think the only term out of all these that we use in German is Soft Drink. It therefore is also the word I use when I speak English.
Edit: Actually we also have the word "Seltzer" but that is a) only carbonated water and b) is something you only use nowadays in German if you're ancient in age.
I said pop my whole life until I went into the military, where many people did not say it. For whatever reason I started saying soda, and saying pop feels weird now.