I ended up ordering 2 Samsung 850 Evo's (one @ 250gb for the OS only, and a 500gb for my core program use like FSX & other programs). I decided to get another WD HDD (1TB Blue) strictly for on board storage (I already have 4TB of external storage not including my couple of cloud options which are equally as big). I didn't want to go too big on the SSD capacity to keep speeds up and with the storage drive, I will be just fine. My FSXA install is bloated up to 345gb which is the single largest program I have running but to be honest, on the next install, I will be trimming the size of FSXA way down (more or less sidelining a lot of scenery & aircraft that I do not use much or at all). Also, considering my Dell system is already two & a half years old, I didn't want to go too crazy with more expensive SSD options. I am absolutely satisfied by all reports that the 850 Evo will do a good job with what I have and for my needs. On my future system build plans, I am going to go all SSD as well as other higher end gear but by that time, there will be some newer & hotter CPU's & GPU's out which will be more befitting of my goals. I also figure by then, we may even see some new & exciting movement in the Flight Sim arena that's game changing.
Anyhow, I truly appreciate everyone's opinion and experience shared here, it's been super helpful in my purchase decisions.
Thanks!