Here are some employee appreciation quotes that I found:

- "I am constantly impressed by your performance. Thank you for your hard work!"
- "Thank you for using your remarkable talents and skills to fuel our mutual efforts."
- "I’m amazed by how you maintain your performance while taking on even more work. You’re a superstar!"
- "No one is irreplaceable, but some folks you never want to have to replace. We are sad to see you go, but excited to see what you do next! Your successor has big shoes to fill."
- "Hard work beats talent if talent doesn’t work hard."
- "We think, mistakenly, that success is the result of the amount of time we put in at work, instead of the quality of time we put in."

I hope these quotes help you with what you're looking for!