[CyberFonic]

I have worked for companies that used both. Based on those experiences:

Use Power RISC with AIX in established IBM user organisation that wanted to run Unix software so we ported existing software to AIX.

Use existing s390 system running several core systems, to run Unix partitions to deploy software already written for Unix in C.

I have never even heard of any company not already being an IBM account migrating to either of those systems. The capital and operating costs are typically far higher than for comparable performance x86 based deployments. Technical staffing is much harder still.

[mikewang]

>I have never even heard of any company not already being an IBM account migrating to either of those systems.

If this is true, this line may be another reply to my question.

[tgflynn]

There are certainly companies that have experimented with Power, including Google, but I've never heard of any large migrations either.

One other consideration is that Intel chips come with closed source and completely opaque logic embedded in the silicon, such as the Intel Management Engine.

As I understand it Power is now a fully open source architecture and you can get a system with fully transparent firmware (at least if you buy a non-IBM system). Depending on your security needs and threat model that may be an advantage, but I doubt it's a significant enough concern for most companies to justify the lower price performance ratio.