PS5000 Sata array 16 drives - Raid for best performance and greatest capacity

Good afternoon All

I have studied the vagaries of the various raid options and was wondering if anyone has a practical insight using PS5000 SATA arrays? Basically the array will provide backup drives to VMs so which Raid would be best for performance and capacity? I was pondering Raid 50 or Raid 6 as the array is a distance from my office in a data centre to that there could be 2 failures before disaster...

Many thanks