"You will want to" usually is a suggestion, based on some situation.
Examples:
"You will want to study for that exam tomorrow."
"You will want to take an umbrella; it looks like it might rain."
"You will want to leave in the morning."
"You will want to eat breakfast before your workout."
"You want to" is more a question or confirmation.
Examples:
"You want to take the train?"
"You want to get coffee tomorrow?"
"You want to paint it blue?"
"You want to buy this dress, right?"