I really appreciate it.
我很感谢.
You're one in a million.
你真是个大好人.
You're the greatest.
你最棒了.
Thanks to you (we made it on time.)
都要多谢你(我们才能准时完成).
I couldn't have done it without you.
若是没有你,我不可能做到.
I'm truly grateful for your help.
我非常感激你的帮助.
Your help is greatly appreciated.
非常感激您的帮助.
I'd like to express my gratitude.