The promise of free air travel seems too good to pass up. Simply sign up for a credit card, the offers say, and you’ll get enough points for a round-trip domestic ticket. That’s fine for one trip, but which kind of travel card will earn you the most free travel over time? Is it the airline card or a bank card? Here’s some tips to help you decide.

Airline Card

If you’re loyal to an airline and travels a lot, choose an airline card. You’re likely to earn the most rewards this way. Smaller airlines use different conversion formulas. Airline cards usually aren’t as generous as bank cards, but one might be worth it of you can score a decent up-front bonus – 50,000 points is a good number to shoot for...