First of all, geographically speaking in the United States, very few locations actually use the word "soda" to describe soft drinks. There's some pockets in the central midwest and Wisconsin that use "soda", some places in New England and a few places on the east coast that use "soda" and California. That's basically it, besides a few rare counties here and there that use it, mostly due to California's influence on the media.
The rest of the United States overwhelmingly do not use "soda". Instead they use "pop" and "coke". Vast majority, geographically. Doesn't work out like that by population because of the very high populations in the areas that use "soda". In the north, it is "pop", in the south it is "coke".
Anyway, my preferences. I like Dr. Pepper and Sierra Mist. I prefer Sierra Mist, especially since they started using real sugar. It tastes much better than it used to when it used corn syrup. If those are not available I get the next closest thing I can find.