Here are the two contenders I found for a new card for myself:
1. Citi Double Cash Back Card - offers 1% back on purchases and 1% back on all payments for a total of 2% back
2. Priceline Card - offers 2% back on all purchases plus bonus % on certain categories of Priceline purchases
The verdict: Citi Double Cash Back Card because the card itself has a better design and my boyfriend already has a Priceline card, which we use on all Priceline purchases. Diversifying the card benefits in one household makes sense.