If a chemist were concerned with how many unpaired electrons there were in sulfur, which of those would be most , and why?

The best way to know would be knowing what the electronic configuration of the element is. The electronic configuration of sulfur is 1s2 2p2 2p6 3s2 3p4.  The p subshell can house a maximum of 6 electrons, but at this time it clutches 4 electrons, which means that sulfur has 2 unpaired electrons, both placed in the p-subshell. Or it could also be seen easily in the Lewis Dot Structure of Sulfur, you can see that there are two that has no pairs. 

They are all full and don't need any more electrons in there outer shell.