I think anything short of cash isn't worth it. Cash has the immutable property of being able to buy and pay for anything. Why lock yourself into a single option for spending.
The following are my personal criteria for using cash back cards.
- Can I pay it off each month? If no, then I don't need a card
- How often do I get cash, and how do I get that cash? (Yearly or monthly, as a check or some other method...)
- Are there any fees? If there are fees that I don't need that card.
If the card meets those three criteria then I can safely use it. I personally use a card for all my purchases (never ever a debit card) because I can pay it off each month. This is a dangerous tightrope I walk, and it can (and has) get me into real trouble.
In your case, so long as there are no fees and you can pay off the card, get a cash back offer as your best bet.