There are a lot of great credit cards to get cashback (Amex Blue Cash, Chase Freedom, Discover IT, many others) but this is a pretty great deal if you already have a paid Sam's club membership IMO.
New Personal and Business Sam's Club MasterCards
Earn 5% cash back on Gas Purchases
(up to $6000, then 1% on purchases after)*
Earn 3% cash back on Dining and Travel
Earn 1% cash back on Other Purchases*
No Annual Fee (Sam's Club membership required)
Online Account Management (SamsClub.com/credit)
Rewards percentages depend on the type of purchase made (5% for gas purchases at U.S. and Puerto Rico Sam's Club and Walmart fuel stations, and at Gas Stations located in the U.S. and Puerto Rico (but excluding purchases at fuel stations at wholesale clubs (other than Sam's Club), certain supercenters, and supermarkets), for up to the first $6,000 in gas purchases each year and 1% thereafter; 3% for dining and travel purchases (excluding purchases at wholesale clubs other than Sam's Club) and 1% for all other Eligible Purchases).