I have StopTech Street Performance currently on my Miata and X3. But the best aggressive pad for street use that I've encountered so far has been the Axxis ULT (formerly known as Ultimate).
Compared to the Stoptechs, the Axxis has more initial bite and what seems like a higher coefficient of friction.
I cannot compare other aspects (track, dust) since I've only had the Stotechs for a short while.
2009 E90 M3 ED
2014 X1 28i ED