I don't really like either, but if I had to pick for taste, Pepsi. I think it's sweeter.
This seemed like a good time to tell this story, when I was 10 years old, they had a Pepsi challenge in my K-mart. Of course, they'd love to air a kid on TV, so they asked me if I'd like to take it. I said yes. They gave me cup A and cup B, so I took a sip from both. They asked, "What cup do you think the Pepsi is in?" I said, "Pepsi's in cup A." The guy just lost all expression and said, "You won. Thank you for doing the Pepsi challenge." So like, wtf? I won and I didn't get anything. I wasn't on TV, I didn't get a shirt, I didn't even get a damned can of soda! So, basically, I'll pick Coke for personal reasons cos they didn't screw me over. D:<