For a while, the most popular payment app in the US was... Starbucks. Yes, enough people were buying venti lattes that even dedicated payment services were being left by the wayside. You can't say the same now, though. Analysts at eMarketer have estimated that Apple Pay will be more popular than Starbucks' payments in the US, with 30.3 million iPhone owners using the tap-to-pay option in 2019 versus Starbucks' 25.2 million. The alternatives aren't likely to come close, apparently. Google Pay should have 12.1 million users, while Samsung Pay is poised to have 10.8 million users.