I guess you want to go for LN2? Or just dice?
Like you already noticed 99% is just about the personal preference and not the real performance. If you are benching with a CB-CPU (Haswell) it depends whether you like fast reaction or more a huge mass for buffering and less temperature ups-and-downs.
For CB-free CPUs like Ivy-E you need a pot which has a good surface to reach the lowest temperature possible. However there are some CPUs which have a CB at about -185°C so it can happen that you run into a coldbug after load on the CPU. E.g. when a benchmark-run is over. Xtreme Addict can probably tell more about this.
You can actually buy any of the latest pots as they are all really good. No matter if EK-Waterblocks, KPC or my stuff. Just go by price, shipping-costs, mounting mechanism, accessoires and style.