class act

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Informal One of distinctive and superior quality: "Academy members ... tend to favor films that will make Hollywood seem a class act instead of a hotbed of money-grubbing vulgarians” ( Jay Carr).

Wiktionary

1. n. An entity exhibiting high class especially through refinement of demeanor, conscientiousness of behavior, and/or skillfulness in performance; or an exhibition of high class especially of one or more of those types:
2. n. Used sarcastically, a person, entity, event, or action entity exhibiting the opposite of the above characteristics, i.e., boorish, unprincipled, and/or bungling behavior

WordNet 3.0

1. n. someone who shows impressive and stylish excellence