What are the best contract management and e-signature apps that integrate with HubSpot?

We’re thinkng about using a custom object to accomplish this but would love to have more capabilities such as:

  1. editing the sharing of a document once it’s attached to an object, not just within the files section on hubspot
  2. ability to hide some accounts to other users (ie. if their type is vendor, and we only want to have them visible to whoever needs to manage vendors)