Crucial MX500 2TB SATA for portable external backup... overkill...? I do weekly backup with it, mostly around 150GB a time...

I would go all out 4TB if not becoz of the exorbitant price for 860 EVO, and MX500 tops out at 2TB only.

And 4TB 2.5" internal HDD can't get locally without buying those complete external solution aka enclosures, since I got plenty enclosures lying around.