General:
* Amiable
* Affable
* Cordial
* Gracious
* Hospitable
* Kind
* Pleasant
* Sociable
* Warm
* Welcoming
Informal:
* Buddy-buddy
* Chummy
* Pal
* Nice
* Jolly
More formal:
* Courteous
* Diplomatic
* Obliging
* Considerate
* Attentive
Specific situations:
* Open: for someone easy to talk to
* Outspoken: for someone who shares their opinions freely
* Compassionate: for someone who shows empathy
* Supportive: for someone who offers encouragement
* Trustworthy: for someone you can rely on
The best word choice will depend on the specific context and the nuance you want to convey.