Formal:
* 我想抱抱你 (Wǒ xiǎng bào bào nǐ) - Literally: "I want to hug you."
* 我想给你一个拥抱 (Wǒ xiǎng gěi nǐ yī ge yōng bào) - Literally: "I want to give you a hug."
Informal:
* 我想抱你 (Wǒ xiǎng bào nǐ) - Literally: "I want to hug you." (More casual than the formal version)
* 我想抱抱 (Wǒ xiǎng bào bào) - Literally: "I want to hug." (Can be used with a friend or someone close, implying you know they know who you want to hug.)
Note: In Mandarin, repetition of a character or phrase ("抱抱" in these examples) can make it sound more affectionate and playful.
The best way to say it depends on the relationship you have with the person and the specific situation.