Writing and talking are two big things that we are dealing in our everyday life. Whether we write through emails and chat or start a conversation, we're still executing our social skills/talents. But there are some differences arise between them.
First is putting your words on a piece of paper or typing (on your keyboard) to keep in touch with your loved ones or acquaintances is much better and easier for me. Because I'm not good in expressing my thoughts in person besides you have time to think and edit your words. But the emotions are not present and can't be distinguished by them. So they don't know if you said it happy, sad or angry.
Expressing your words through speaking is a little bit hard for me. I'm not a type of person who talks my thoughts and feelings to people around me. But doing this will show that you're sincere. Why? Because they see through your eyes if you are true to your words. In other words, they see your facial expression and reactions as you talk to them. They can tell if you are just lying to them through the tone of your voice as well.
Anyway, both of them are important if we use fairly. Writing will make your mind sharp and go to the next level while talking will give you more confidence in yourself and improve it also. If you asked me where I am good at, I would answer you writing than speaking. But I should not let my speaking skill just as it is because there is always a way if you want to.