What I think I want out of CPU performance in a new PC
If I'm going to consider building a new home PC (as I sort of am), one of the big questions is what sort of CPU I should build it around. There are a dizzying array of tradeoffs here, and you have to make some of them since features like ECC are only available in some models. In other words, you need to decide what you care about. ECC? Many cores? Advanced virtualization support? Overclocking capabilities? Thermal profile? And so on.
After thinking about it for a while, I think that I have two priorities, and one of them has wound up somewhat surprising me. The unsurprising priority is thermal efficiency and in particular a limit on how much heat I'm willing to have my CPU generate. I want a reasonably quiet PC and that means not generating too much heat, so a midrange TDP is my target (or at least my maximum). Looking at Intel CPUs, I'm probably aiming for about a 65 watt TDP.
(I do still care about multiple cores and multicore performance, and maybe programs will prove that I'm being too pessimistic here.)
Unfortunately, a focus on single-core performance with a midrange TDP probably means that I don't get nice things like ECC, since my impression is that one must give up CPU performance to get ECC if you want to stay with that midrange TDP.