All Purebloods aren't Force Sensitive, there is at least one on Voss and probably more out there.
To the others, Purebloods aren't more respected than Humans, just more than the other species. Actual Purebloods are slowly being bred out, so pure genetic lineage is considered more important than a hybrid one.
Don't forget Sechel. When it comes to Sith and Force-Sensitivity, that was more of Bioware's line at the time, than the current situation in the lore. The point is that Non-Force Sensitive Pureblood's are stll rare and it still doesn't really fit the backstory as well as the other species.
Considering what he see on Korriban for the Sith Warrior (specifically the Assistant Overseer who directs you to your class trainer); there still seems to be a Higher Status for Pureblood's, or their traits of Purebloods are just highly desired. Also, isn't the reason for Sith lineage being more highly prized because it increases the chance of having Pureblood offspring?
Onto the original question, I think the most fitting Species are Human/Zabrak/Rattataki in order of "fitting".