ASUS Z170 MoBos: which will allow raiding 2 M.2s + 2 U.2s still having 2 free sata ports?

[Lupo Grigio]

Hi everybody

I would appreciate a clarification on the possibility of configuring a bootable raid 10 with 2 Samsung 950 PROs + 2 Intel 750 SSDs, still keeping 2 extra free sata ports for hard drives.
I was considering either the Maximus Extreme or the Z170-WS or the Z170-Premium which comes both with a Hyper M.2 X4 and hyper kit for U.2.

Please feel free to suggest MoBos other than ASUS, that would allow a similar solution without entailing a complete deprivation of connectivity. Not a motherboard that lets you have your cake and eat it too, but neither one that leaves you in your underwear just for asking for an nvme SSDs raid 10.

Thank you for your advice.