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.