Apple iMac (21.5-inch, Mid 2011) - Recommended upgrades?

OS: Sierra
RAM: 8 GB (2 GB x 4)
storage: 500 GB HDD (5400 RPM I think)

Initially I was planning on purchasing a 500 SATA SSD, and simply migrating OS to the drive. But then it occurred to me to enable boot camp and have a 500 GB Apple OS and another 500 GB Windows 10 Pro OS. So now my plan is to purchase a 1 TB SSD. I will either purchase Crucial MX500 / WDC Blue 3D or Samsung 860 EVO; probably will go with the Crucial because of the low price and included 9.5mm adapter.

My Question: I'm seeking input on my storage upgrade plan above and anything else that you can think of that would be a worthwhile upgrade. I'd also wondering if an upgrade to High Sierra or Mojave is both possible and advisable. Thank you.