What types of wood is used in your area?
It is primarily a regionally driven issue. Some regions are primarily southern pine, some are doug fir...Based on regional availability. That being said, most common species are available everywhere. Personally, I hate southern pine even though it is capable of the longest spans among the common species (SPF, doug fir, hem fir). It is hard as rocks and gets all squirelly as soon as you break the bands of the bundle. Give me fir, hem fir, or SPF anyday. Treated lumber is nearly always southern pine since fir is a more refractory species (more resistant to treatment).
Check the codes in your area to determine what requirements are in place for studs, joists, rafters, etc. Species is never mandated by code in framing applications, span is.