Synthetic test conclusions
From these data, when can make some preliminary conclusions.
Excluding the RAID 0 setup (which is too prone to data loss) and RAID 1 setup (which focus itself on reliability only), the battle here is between RAID 5 and RAID 10. The former as an higher read speed, but can be severely limited in some write scenario. For this reason, I generally prefer the RAID 10 configuration: it has a very well balanced mix of performance and reliability. The only real drawback is that you lose 50% of total disks space: in some circumstances this space loss can be unacceptable.
Lets move on real word tests now...