Formal:
* Lo que deseo para Navidad eres tú. (This is very formal and would be appropriate for a very special occasion or someone you are very respectful of.)
Informal:
* Lo que quiero para Navidad eres tú. (This is a bit less formal than the previous option, but still respectful.)
* Tú eres lo que quiero para Navidad. (This is the most common and natural way to say it in Spanish.)
* Para Navidad te quiero a ti. (This is a bit more poetic and romantic.)
Slang/More Casual:
* Te quiero a ti de regalo para Navidad. (This is a playful and casual way to say it.)
It is important to choose the translation that best fits the tone and context of your message.