just wanted to clarify that scoreperfect is testmasters (robin singh's company) in texas
so a better question would be testmasters or powerscore?
Testmasters was founded by Robin Singh, but he allegedly co-founded it with a guy who later split off to form Powerscore. Singh was tutoring on his own initially, and I'm not sure when the other guy entered the picture, but he was apparently there pretty early on.
Therefore, the techniques and approaches of the courses are probably pretty similar. Both are very in-depth and comprehensive in comparison to other courses.
PS allegedly provides more material in their workbooks, while TM allegedly keeps their techniques more secretively, and doesn't write them out as much. (The instructor just explains them.) Aside from this, as is frequently stated, it comes down to the individual instructor.