I want to talk to you generally means that you have something you want the person to know.

I want to talk with you would mean you have things to discuss together, more back-and-forth. You want to hear the other person’s thoughts as well.

You should either say: I need to speak to you about… Or, I would like to speak with you about…

The first option relates that you need to say something but there will be no discussion. The second option relates that you would like to have a conversation.

It is generally politer to let the other person know the topic. If it is personal, you can just say “something” or “something personal”.

The next best follow up question would be” which one is correct, I want to speak to you or i want to speak with you?

What do you think?

“I want to talk with you” means that you want to have a chat with someone.