Where should you build a community in 2018?
Really depends on where the people you want to bring together hang out, which apps they use, what kind of behavior you're looking to stimulate, etc.
Agree with Marc. I personally really like communities built on Discord, Slack or Telegram.
Discord and Slack since you can chat about different topics in different channels.
Telegram since it's so minimalistic and smooth to use on both desktop and mobile.
But I would probably also run the community on something like Facebook or Spectrum (or have a separate site like this one) for more ongoing discussion etc. but not post as frequent.
All depends on your target audience. Non-techies? Facebook. Techies/non-techies? Slack. Advanced professional hackers or indie hackers? Telegram.
well it will be for skiers and boarders. I would like to monitise in future a la nomadlist. Telegram is the cool option but its maybe an extra hurdle. (even techies i know haven't heard of it) Maybe can try telegram and slack a/b and see what people use more
Slack is better for your use case I think, given the fact you're gonna monetize it, it has more advanced capabilities for managing (e.g. channels) and adding extra functionality with apps/bots.
+1 what Marc said. Maybe another question: how hard is it to get an existing (strong) community from one platform like Slack etc. to your own service/product in the end?
You go where your target audience is, what they like and what they don't
Facebook Groups or Slack or Telegram.
I use Mighty Networks for my community and love it. It has many features that Facebook Groups/Slack has, but is very customizable and you can enable members subscriptions and make money on day 1.