What's is your preferred RAID Level?

I'd say all things considered, but cost can be a huge factor in determining how much one is willing to give up in terms of storage space, with respect to gains in either performance or redundancy.

For example For a nice balance between sheer performance on the one hand, and high availability and failover on the other, I might be inclined to just choose RAID 10 as a matter of course, considering the increased read and write capabilities, but when cost is factored in, other alternatives like RAID 6 will yield much more in terms of storage with a sacrifice in performance.

When deploying HA storage schemes in server clusters, we've already invested in greater redundancy and removed the RAID controller, and to be sure, even the server, as a single point of failure, but on a single machine, where would your preferences tend to lie after you've factored in cost vs availability vs storage volume - do you strive for a happy medium? Maximum storage? Maximum performance? And which schema do you find yourself leaning towards more often than not?

Your thoughts?