Which adjective best describes someone who is approachable and easy to communicate with?

The adjective "affable" accurately describes someone who is approachable and easy to communicate with. An affable person is typically friendly, sociable, and welcoming, making it comfortable for others to engage in conversation. This characteristic fosters open communication and helps create a positive interpersonal atmosphere. In contrast, the other options suggest traits that would hinder approachability: being gruff implies a roughness or stern demeanor, antagonistic suggests hostility or opposition, and withdrawn indicates a tendency to be detached or reserved, all of which would make communication more difficult. Thus, "affable" is the best fit for describing someone with a warm and inviting manner.