250GB SSD + HDD.
Depending on what motherboard and budget, NVMe drive instead of SATA.
Why?
The 120GB is right on the edge of TooSmall for an actual OS drive.
The Optane is good as a cache for an HDD, but an SSD is fast across the whole space.
So...what are the rest of the parts, what is the whole budget, and what do you use this for?