I think that would greatly depend on what motherboard you have.
If you have a board with M.2 support, or enough PCI lanes to use a PCI SSD or M.2 drive in a PCI slot, then an M.2 + SSD would be the fastest, but you'd also want at least one additional HDD, minimum, as a backup. You'd want that anyhow, regardless which of the configurations above you chose.
Does your motherboard have an M.2 slot? If not, then Blackbird's recommendation is the best as long as you use a 7200rpm high density drive. Most desktop HDD are 7200rpm anyhow, but there are still some 5400rpm models out there. Most 5400rpm drives are 2.5" latptop drives, which you can still use in a desktop, but are not normally as fast unless they too are high density drives. In that case, sometimes they actually benchmark faster than a 7200rpm drive. Just depends on the drive.
In any case, SSD + SSD is always going to be WAY faster and these days the longevity of SSDs is probably just about as long as you can reliably expect a HDD to last anyhow, with one caveat. If you are WRITING a great deal of information to the drive, constantly, and consistently rewriting on previously written blocks, an SSD might not be the best choice for the storage drive.
In reality, if that is the case you'd probably be best off with an M.2 or SSD + redundant HDD in RAID. Still depends on what motherboard you have. Hard to really make any kind of solid recommendation without knowing that.