Please create a connector for Hubspot, especially for contacts.
Hubspot Service Tickets
I'd love to see a proper HubSpot connector too.
In the meantime, if you just need to get contacts in to HubSpot, you can use the HTTP Connector to POST your data into a HubSpot form, via their Form API. It's kind of like proxying one of their own signup forms, and kicks off all of the automation stuff as normal.
I ended up writing an article about it for some of our clients, if you're interested in a bit more detail:
Would really appreciate an easy integration with MS flow and Hubspot