Words starting with X are quite rare In English language when compared to other letters. So the scarcity of the positive adjectives that start with letter x isn't surprising.
Positive adjectives starting with X
Make your vocabulary more xenial with these positive x adjectives.
Xenial: friendly; hospitable.
Xenodochial: friendly to strangers or guests.
Xerarch: developing, growing or having its origin in a dry place or habitat.
Xylographic: pertaining to woodblock printing art.
Xylophilous: growing or living in or on wood.
“Xenial' is a word which refers to the giving of gifts to strangers. . . . I know that having a good vocabulary doesn't guarantee that I'm a good person. . . . But it does mean I've read a great deal. And in my experience, well-read people are less likely to be evil.” ― Lemony Snicket, The Slippery Slope