Mainly a gamer, I bought one as its a good platform, Ryzen 7 and Intel mainstream are quite limited due to lack of IO, I already had a maxed out z77, the new platforms offered nothing more, Intels HEDT was too pricey, 1900X was all I needed to get on a decent platform with scope to grow further.
A z270 supercarrier and an i7 would have been a reasonable alternative for gaming to get more lanes via PLX, I was considering it but Intel released new stuff, basically obsoleting the old stuff, seeing as support for my old board pretty much died with release of new CPU it put me off, CPU not so critical for me, game at 4k, it's all about GPUs, much rather have a system that can take what ever I throw in it. 1900x is the quickest Ryzen if you don't need a stack of threads, highest base clocks, so all core 3.9Ghz with boost and then XFR up to 4.2 with lighter loads.
If you are never going to have more than one NVMe drive and 1 GPU, the 8700 is probably the place to go, though I'd still be tempted to go 7700k, its cheaper, has good motherboards like the gaming 9 + supercarrier with PLX/PEX chip allowing a bit more expandability. These will no doubt surface on z370, but its a bit new and hardly exists so probably won't happen until early next year.