Which credit card to pay down first?

I’ll be starting a new job soon. This job will give me some extra income that I want to apply to paying down my credit card debt. I’ve heard different things about which card to pay down first, and I have three candidates:

1. A card that is over the limit by 50%, but which I am not paying any interest on.
2. The card which has the highest percentage rate, but is under the credit limit.
3. The card which is closest to its limit but has a comparatively low percentage rate.

My interest in paying down this debt is not only to get it off of my back, but also to increase my credit score.