Really, credit cards aren't paleo? (Neither are computers. Or the Internet. Doy.)
We have a Chase Freedom. I like that right now I get 5% back at grocery stores, and I like that I always get 1% cash back. I like that I can download a .csv file of our monthly expenses and keep better track of our money and where it is going. I like being able to pay at the pump at the gas station and NOT have to lug my kiddo out of the backseat to pay in cash. I like Amazon.com for random household purchases and bulk purchases. I like being able to hold my baby on my hip and swipe a credit card at the store - I would never be able to manage cash and change with only one free hand!
We pay our credit card off IN FULL every single month. Credit cards do not have to be evil; rather, they can make your life easier, make it easier to track expenses and give you perks, like cash back. Consistent use and proper use of credit cards is good for your credit rating, which will do all sorts of happy things for you should you ever want to purchase a house, etc.
Anyone who is criticizing you for asking about a good credit card for the purchases that you want to make on a regular basis to support your paleo lifestyle (groceries, five fingered shoes, whatever...) needs to take a step back and remember that we're not doing historical reenactment. We're making the right choices for our specific circumstances. For some of us, myself included, this most definitely involves using a credit card. Responsibly, of course.