New rig build - DDR4 memory frequency advice

[boxman2000]

So I'm about to upgrade my rig to an 8086k (not the unbinned version) and currently looking at an MSI Z370M Mortar (Micro ATX) to go with my EVGA 1080Ti FTW3 but I'm stuck on the RAM to go for.

I'd like to have the option to overclock the setup at some point and don’t want the RAM to be the bottleneck so just trying to future-proof myself. At the moment I am considering the 4000Mhz range and looking at the following:

• Team Group Xtreem "8Pack Edition" 32GB (4x8GB) DDR4 PC4-32000C18 4000MHz Quad Channel Kit Black (MY-096-TG)
• Team Group Xcalibur RGB 16GB (2x8GB) DDR4 PC4-32000C18 4000MHz Dual Channel Kit (MY-09T-TG)

I’ve read around and there are varying opinions as to the real world use of anything above 3600Mhz but have been out of the hardware game for a long time, hence the question.

The motherboard above can handle 4000Mhz DDR4 and I’m not interested in flashy lights but need to keep price below the £450 for 32gb but if 3600 or even 3200 will be absolutely fine, any suggestions would be really appreciated please.

Thanks