General Synonyms:
* Fascinating
* Captivating
* Alluring
* Enticing
* Compelling
* Engrossing
* Inviting
* Appealing
* Interesting
* Exciting
* Provocative
More Formal Synonyms:
* Intriguing (most formal)
* Alluring
* Beguiling
* Captivating
* Enthralling
* Mesmerizing
* Spellbinding
Words Emphasizing Mystery:
* Puzzling
* Mysterious
* Enigmatic
* Perplexing
* Inscrutable
Words Emphasizing Curiosity:
* Curious
* Intrigued
* Stimulating
* Provocative
* Thought-provoking
Words Emphasizing Desire:
* Tempting
* Alluring
* Attractive
* Luring
* Appealing
The best word to use depends on the specific context and the nuance you want to convey.