HDD: A couple of Seagate Barracudas in either a RAID 0 or RAID 1. I've never experienced a hard drive crash, ever, so I'm sort of ambivalent on which one to use.
Avoid RAID 0. It can enhance your disk performance slightly, true, but it actually reduces longterm reliability, because every disk in the array is vital to your data integrity; there's no redundancy. So if you buy X drives with Y hours MTBF, the actual MTBF for the array is Y/X; not good. If you really really want RAID 0, buy 4 drives and use RAID 0+1.
-BP