When I was a kid, my best friend's family came from Michigan, and they would always say "pop" when I was at their house, even though CA is strongly "soda". That is the only place I can actually recall hearing something other than soda. Even when I used to travel a lot for work, and was in "pop" and "coke" regions, I can't recall hearing either of those words, or "soda" for that matter. Any soda related talk was along the lines of, "Can I get you something to drink?" "Yeah, I'll have a [name of beverage]."
Though I very rarely drink soda anymore, when I do, or did, I've never referred to it as soda, but always to the brand name of whatever I was drinking.