Hello Team - when it comes to RAID configuration to Oracle DB 10g and above what's the best practice OR what have you seen being implemented the most out there?

I know this is probably a question that will lead to personal beliefs or the famous (but always applicable) "it depends". Regardless, I would like to have your opinion on this or if you could point me to more of a more formal answer from us is fine to.

The reason I ask is that, I do get a lot of questions around what would we recommend as best practices. I do a lot of overlay support for overseas partners so I  don't get the privilege of having huge access to end customer to clarify certains things. So, I work a lot out of assumptions and I have to rely a lot on best practices to at least present something that doesn't look like completely off.

Anyways; any guidance will be appreciated.