This is a hotly debated topic amongst your fellow OT members and it's time for you to weigh in!
Harry Reese was the man who made Reese's peanut butter cups. The dude's name is Reese. If something belonged to Reese, you'd say it was Reese's. Reese-us.
Who is Ree See? I don't know any Ree See. And either do you. Vote now!
Also, Reese's Pieces rhymes just as much as Reesee's Peesees. And you KNOW how pieces is pronounced.