Giving compliments :

– You look … (eg. You look amazing).
– I like / love … (eg. I like / love what you are wearing).
– You are … (eg. You are incredible).
– You ooze confidence. (eg. You have a lot of confidence).

Idioms :

– You knocked it out of the park. (You did really well)
– You’re the king of the hill. (You’re the most successful / powerful)
– You nailed it. (You did very well)
– Top dog. (You’re the best)
– You’re the bees knees. (You’re the best)