I normally say Soda, but in So Cal, everyone calls everything Coke. If you want a Grape soda, its a coke, orange slice...Coke, Pepsi...Coke.
But I know all of my friends who have moved here from the MidWest call it Pop...just my observation. Most notably, the Minnesotans, say pop, but when they say it, it is often perceived as "pap."