I grew up in the Midwest with New Yorker parents and then when I was 17 moved to Texas where I spent 17 years before spending the last 11 in Arizona. In other words I don't know where the fuck I'm from, and I say soda.
It's not laziness. It's that as the country moved west transportation technology improved. One or two days' journey in 1776 was a lot different from one or two days' journey in 1900. The counties were designed so that people could get to the county courthouse in a reasonable amount of time.
Also, the west is less densely populated. Loving County, Texas (see map), is one of the furthest west of the "small" style counties, and it has a population of only 52 people in the whole county.
Unfortunately, despite your kind foresight in providing an unlimited (or limited to an as yet unknown quantity) character field, you have not also provided any user-accessible Markov process delineation tools by which I may display the simple matrix equation whereby I (existentially) derive that term that I find most appropriate given the specific socio-psycho-political situation in which I find myself desirous of delineating my requirement for a sugared, carbonated beverage. Laying this shortcoming aside, [I find that I am also spurred to make this brief response to your survey that I may remedy the sad dearth of unusual responses that I find are (inexplicably) lacking from your Washington state respondents.] Putting that by the way, I shall bring myself directly to the point and address this issue directly, coming immediately to the point and not beating any further around the bush. I would say, in the fullness of time, all things being equal, taking one thing with another, and--generally--with an eye toward the only certainty that we all live with that the universe is constantly in flux (or immutable--can't remember which)--it rather depends.
I used to agree tha Dr. Pepper and Diet Dr. Pepper tasted the same, but after my friend started working there and getting free soad I can taste whatever crap sugar they put in there. Still the best diet soda though.
so what are the "other" words besides soda, coke and pop?!?!
I grew up in the South. The generic word for a soft drink was coke. If we wanted anything other than coke, we ordered it by name. I'm assuming that's what they mean by other words. (They could also mean "soft drink" as one of the other words).
edit: I just found the county I grew up in on the map. We were in one of the 80-100% coke counties.