Test riding them will help make your decision. (Stumpjumper Comp or Stumpjumper FSR Comp?) The Kona seems a bit more of a big hit bike. Questions to ask yourself are what is your riding style, types of trails you will ride, etc. You'll be very pleased with the Maestro Suspension on the Giant, but all are good choices. You'll also be quite happy with the Specialized. I don't have much knowledge on the Kona.