Picky
Someone who is picky is very selective and hard to please, often focusing on small details and preferring only certain things.

Examples:
1- Emily is so picky about books that she only reads ones recommended by her favorite authors or those with five-star reviews.
2- Steve Jobs was so picky about design and user experience that he insisted that the insides of Apple's computers be as beautifully designed as the outsides, even though users wouldn't see them.