i would say the RAID 10 array is best as it offers the best performance and fault tolerance combined into one package. The downside of RAID 10 is the disk cost (no of disks required)
Maybe the question was misunderstood. I proposed two scenarios for how to configure 4 disks to hold data. A single RAID 10 with 4 disks is just as fault tolerant as two RAID 1 drives - each can lose 1 disk per pair. Likewise the disk cost is the same in the question I asked.
As for performance, I'm looking for something solid to show that RAID 10 would be better than RAID 1 or vice versa. I was really hoping someone knew enough about what's going on under the covers (e.g. IO paths, threads, etc.) to make it clear.