I don't know if this is specifically regional to a particular part of the coast, but, folks in california call it "pop". Same with northerners (PA, NY)
Where in california do you live? in norcal it's soda.
It's odd that people say we down here in the South usually just call it Coke (and living IN Atlanta, home of Coca Cola, people think that even more so), but most of the people I know call it soda.
Brit here. Fizzy, pop... They're kind of informal and I'd use it when talking to my family. However, if I wanted to impress the Ladies I'd definitely say soft drink.
So far no Ladies have been impressed but I'll keep trying.