Well you might want to fill out some details of budget and goals so we can give you more specific advice, but in the meantime I can offer some info on the 2 platforms.
Ryzen has a lot going for it right now with the extra cores/threads over intel's 4/8 max on the consumer line.
While in gaming they generally fall behind kaby lake from intel, they tend to have more solid frametimes and consistency when streaming services are added on, meaning higher quality settings for the stream itself.
The 8 core Ryzen 1700 seems to be the sweetspot, as you get an 8/16, with a decent cooler and overclocking up to 1800x speeds without paying the premium.
Intel is faster clock per clock, but streaming benefits from greter core/thread count to spread the work. So while the 7700k is faster, it loses in the streaming department at least relatively to AMD for the reasons above.
The next generation Coffee lake, there are 6 core models in both i5 and i7 variants that will probably outperform AMD (but likely be more expensive too.)
It looks like it could be compatible with z270 and z170, which only means a processor/bios upgrade to get that. But we don't know anything for sure yet like speeds, prices, or compatibility and probably wont for a couple months.
Ryzen won't update with zen2 until next year, but is supposed to be compatible with currrnt motherbpards.