If you can afford them, Michelin or Pirelli seem to be the Gold Standard. I have Hankook's on a 97 and an 09S. I never track the cars. I do run them hard in the local mountains. I have been very pleased with their wear and performance so far.
https://www.tirerack.com/tires/tires.jsp?tireMake=Hankook&tireModel=Ventus+V12+evo2&partnum=335YR9K120XL&vehicleSearch=true&fromCompare1=yes&frontTire=335YR9K120XL&rearTire=635YR9K120XL&autoMake=Porsche&autoYear=2009&autoModel=Boxster+S&autoModClar=&autoMake=Porsche&autoYear=2009&autoModel=Boxster+S&autoModClar=
The 09S eats rear tires. +/-8500 miles on the last set of Pirelli rears. And I never turn the traction control off