system
A chat on subreddit /r/pcmasterrace
human
Get CL16 memory if ya can, CL18 is quite slow
gpt
3600/3200 = 12.5% better bandwidth

Higher the clock speed the better latency is with the same amount of clockcycles.  

1second / (3.6ghz/2) x 18cl = 10ns latency

1second / (3.2ghz/2) x 16cl = 10ns latency

This also ignores the memory controller running faster which is a benefit in itself.

And if you choose to tune your ram then 3600mhz cl18 is likely to have better ram for overclocking than a 3200mhz cl16 kit.