For those wondering why I bothered: last year I moved the household to 4K HDR-capable smart televisions, and the only device I have which can utilize this resolution at all is the Xbox One S right now.
Initial Upgrade Experience:
PS4 Pro upgraded by having me connect the new PS4 Pro to the old PS4, and it proceeded to copy over all the relevant files on to the new system, which took about 2.5 hours (the old PS4 was a 500GB HDD edition). Contrary to information online, I was able to detach my external hard drive and plug it in to the new one (once it finished the transfer) with no issues.
Xbox One X basically required some OS updating and then moved my account over while online. I took about an hour to migrate all games off of my old Xbox's internal hard drive to my 2TB external drive, but once that was done it was plug-and-play.
So both experiences were not bad to perform the account/game migration, but Xbox One X was a little faster and easier.
The 4K Movie Experience:
Ps4 Pro is apparently not designed with UHD Blu Rays in mind so I didn't even bother. Xbox One X is specifically designed so you can watch UHD Blu Rays as intended. It works...when I insert one of the few UHDs I've shelled out money for, it plays, and looks good. Not like "holy cow" good....all those people talking about how shocking the upscaling effects are, or the UHD quality or the HDR and so forth are all apparently gifted with more precise vision than I am (or only recently discovered this high def phenomenon), but the resolution feels "right." One thing for sure...anything less than a 1080p Blu Ray feels like an awful viewing experience these days. I need to upgrade my Star Trek film DVD collection some day!!!
The 4K Gaming Experience:
PS4 Pro is more like a "PS4 1.5" incremental upgrade. It has more power, and can render and process the games better, but everything I've read indicates that the console balances between graphical performance and framerate for the best experience. The result is games which you can (usually) tell are more enhanced than 1080p resolution, and often with smoother running experiences. I found this most notable in Destiny 2 and Watchdogs 2, and Horizon: Zero Dawn continued to look great, but some other games (such as Star Wars Battlefront 2) didn't look all that improved. Overall my experience so far has been, "Hmmmm....yeah, I think this looks a bit better. Wait, what did I pay for again???"
Xbox One X is not an incremental improvement, it's a hot new blazing machine and it's not bashful about showing this power off. Every game I've looked at so far which is on the "Enhanced for XB1X" list isn't just noticeably better, they're all shockingly better....running at a smooth framerate at 4K resolution. Games like Forza Horizon 3, Gears of War 4, and Halo 5: Guardians are simply amazing to look at. Halo 5 in particular is so sharp that playing it at the higher resolution is a huge contrast graphically to my prior experience.
The enhancements for 3PP games on XB1X are a bit dicier so far, but there's no denying the performance improvements. Most notable is all of Ubisoft's titles: I have not seen Ghost Recon: Wildlands like this before, with 4K native resolution, smooth framerates and all the graphical bells and whistles turned on (that game still vexes and tantalizes me at the same time, though). I could not achieve this on my PC (and to ugprade my PC to get this would cost a lot more than the Xbox One X did!) Titanfall 2 also looks amazing at 4K.
So: if you only need one console to provide a 4K experience, Xbox One X is it. Hand's down, it's the better overall experience for the "current gen" console systems. PS4 still has a lot of love, but for the foreseeable future, until Sony catches up, Xbox One X has effectively become my new top dog in terms of gameplay power and performance.