I use British Airways Avios to book award flights on American Airlines.
Brad's Deals Editor Mark,
Earn 50,000 bonus Avios after you spend $3,000 on purchases within the first 3 months from account opening on your British Airways Visa Signature® Card. Every calendar year you make $30,000 in purchases on your British Airways Visa card, you’ll earn a Travel Together Ticket good for two years. You will earn 3 Avios for every $1 spent on British Airways purchases and 1 Avios for every $1 spent on all other purchases. There are no foreign transaction fees when you travel abroad. This card is also is enabled for contactless payment.