Here are some contenders, each with a slightly different nuance:
* Hello: This is a universally welcoming word, used to initiate a friendly conversation.
* Welcome: This conveys a warm and inclusive feeling, often used to greet someone to a new place or situation.
* Thank you: While technically expressing gratitude, it can also be a gesture of kindness and a way to show appreciation for someone's presence.
* Friend: This word is inherently friendly and evokes a sense of closeness and connection.
* Love: This word expresses the highest level of affection and care. It's incredibly powerful and can be seen as the ultimate expression of friendship.
Ultimately, the "friendliest" word is the one that best conveys the specific emotion or sentiment you want to express.