First of all for those that don't already know, "M.2" only refers to the form factor of an SSD, I.e., the actual physical shape of the part itself. It's small and sleek, like a stick of gum. Ideal for laptops because of size restraints.
In a desktop you've got plenty of space, so the only reason you'd care about using an M.2 is because they can give you faster data transfer, compared to an SSD that you connected with a SATA cable.
That's literally the only advantage, that I can see, that matters for a desktop build.
But not all M.2 SSDs, which plug in to PCI slots, actually use the PCI protocol. Some, intended for laptops, simply provide the space advantages but not the faster connection. These offer no advantage to a desktop build.
So from what I can tell, when you're selecting an M.2 SSD for a desktop PC and you want the advantages to actually matter as much as possible, the practical steps are:
1) Make sure the drive supports NVMe a new, fast, PCIe data transfer technology.
1.b) Obviously you want to make sure your mobo supports NVMe. I personally have a Z170-A mobo, which does indeed natively support M.2 NMVe.
2) pick a budget
3) get the largest capacity drive that fits your budget.
Is there anything else to it? What do you guys think? Please share experiences.
Also I'm new to this sub, first post, so hello everyone!