quandour

Hm, that's actually quite a significant price difference between the 860 EVO and the NVMe drives.
At the minute, you're most likely not going to notice a difference between a good SATA and a good NVMe drive. Game developers though will likely start taking better advantage of the speeds of NVMe drives, since the next-gen consoles ship with such drives.
 
Whether that's worth the extra $25-30 is up to you.

If NVMe fits your budget, then I'd go for it. 
 
Both the SX8200 Pro and SN750 are solid drives - they're pretty much on par, other than fact that the SX8200 Pro pulls slightly less power, though if you're going to have a heatspreader on it and/or have decent case airflow, it's not like it'll matter anyway.
I'd get the SN750, since it's cheaper.

For the same price I would go with the HP unit. 16gb of ram is necessary I'd say.

the dell unit