Playing Sonic Adventure all day on 9/9/99 permanently etched Open Your Heart into the back of my skull, and endlessly replaying the Sonic Adventure 2 demo did the same for City Escape... but I think my favorite might actually be the SA2 version of It Doesn't Matter.
Can you feel the sunshine? Does it brighten up your day? Don't you feel that sometimes, You just need to run away? Reach out for the sunshine, Forget about the rain. Just think about the good times and they will come back again.