Which DDR4 would you buy?

[fosk]

Let's assume the prices are roughly the same to the point it's not a factor.

DDR4 16GB [2x8GB] 3600Mhz C16 - G.SKILL Trident Z RGB [F4-3600C16D-16GTZR]

DDR4 16GB [2x8GB] 4266Mhz C19 - G.SKILL Trident Z RGB XMP 2.0 [F4-4266C19D-16GTZR]

I am under the impression higher MHZ ram can run at lower MHZ at lower timings then lower speed ram can?

 

[Woomack]

Both kits are on the same Samsung IC. Higher frequency kit has higher chance on better overclocking. However, both will run about the same at 3600 so buying 4266 kit you get higher chance on something like DDR4-4400+.
On most new platforms higher frequency gives more than lower latency. It's because fast CPU cache covers most of the latency issues. Pretty much every memory benchmark is showing now memory+cache speed, not only memory. The same memory stability is connected to IMC+cache stability.

If you are playing games and not much more then 3200 CL14 seems optimal. 3600 CL16 cost often about the same and is a bit faster. Still most these kits will be based on the same Samsung IC.