FWIW I have been evaluating the situation and considering the upgrade since the summer holiday. Main reason was gaming and also my interest to get into VR. Originally I was quite motivated by Ryzen (1700 in particular), but more info I got more I got confused and at the end I decided to pass on Ryzen (first gen at least).
Do not take me wrong, Ryzen is a great arch, and Ryzen 7 are good chips for almost everything except the gaming. For gaming (and even more for VR gaming) you need:
1) High IPC
2) High single-threaded perf (even if the games can utilize more threads/cores, the distribution of the tasks is never symmetric, so one thread is always kind of "master").
3) High mem perf.
For 1) and 2) Intel offerings were better (comparing to i7-7700(K) at the time) and for 3) one must overclock the memory to 3200 to get comparable memory perf from Ryzen. Unfortunately memory overclocking on X370 turned out to be a nightmare where no one was able to tell, which motherboard with which DDRAM will be able to do it.
So I decided to skip Ryzen. Then Intel came out with Kaby Lake refresh (i7-8700) which was basically only improving on all aspects. The only problem with i7-8700 is it needs a new chipset Z370, which seems to be only interim solution which should be replaced soon by Z390 next year.
Then Pimax arrived with its 8K HMD and I said to myself it would be probably easier to simply wait it out, by using Pimax as an excuse. So I will build my new PC (for games and VR) only after I got the headset. I hope until then the things will get sorted out. Maybe z390 will arrive, or Ryzen 2nd gen with better memory controller...
I admit I never considered Threadripper, because of a) price, b) I never saw any advantage of Threadripper over Intel standard consumer line for my particular use case. Since you are shopping for Threadripper or Xeon, I guess your main usage is not gaming (or VR gaming) but some "serious work", so I guess then Threadripper is the way to go (factoring in perf per dollar).
For VR however, I hope, either Intel fixes their consumer platform with more PCIe lanes (hopefully in z390) or AMD fixes their memory arch (in Ryzen 2nd gen) and either will come early enough so I could use it for my new build for Pimax headset. Adding Volta on top