Did a lot of research, finally bit the bullet, and confident I made the right decision.
It took a while to filter through all the competing brands and models, but the DS918+ is easily the most powerful box in this price range.
I wanted to consolidate all the photos and videos from various vacations and events over the years, but figured any of the NASes could handle that chore effectively. The part that really separated the DS918+ from the rest was its ability to transcode videos on the fly, with very little CPU overhead.
Considering Transcoding is going to be the most CPU intensive task I will ever do on a NAS, the built-in hardware transcoder saves the day. It will transcode massive 1080p-60fps GoPro videos, to my iPhone, while on a different network, in real-time and only consume 5-6% CPU. And the fact this comes with 4gb of memory and slots for SSD Caches, means you will never be disappointed by performance.
The only other option worth considering is the DS718+, but once you do some pretty rudimentary math, you'll see it's cheaper to buy 4x 4tb drives (12tb usable) than it is to buy 2x 12tb (12tb usable). Throw in the fact that 2GB of memory isn't substantial enough to run Plex and system services, you really only save a small amount getting the DS718, and then you have zero upgrade paths. With the DS918+, I bought 2x 6tb drives, and if I ever want to Double my capacity, I can buy one additional 6tb drive. That's awesome.
The Synology software is fantastic and is as simple as installing an App from iTunes. You know it's been tested and configured to work with your hardware, so you won't be in the weeds trying to figure out why PHP isn't starting for some reason. No hair pulling, everything has been super easy and it is packed with features, notifications out of the box, and even works my with cheap Cyberpower UPS.