Apple
It's faster than monkeying around with plastic or cash, and I love the idea of being able to leave home without a wallet. While I don't own an Apple Watch, I hear it makes Apple Pay even easier.
Apple Pay is more fun than alternate methods. You get to see the phone analyze your fingerprint (in a second or so) and then validate payment with a pleasant tone and vibration. You get to impress other people, who often react with a wow.
It's safer, too, transmitting information through a one-time code that hackers can't skim.
As much as I like Apple Pay, however, I'm in the minority for now. Up to 80 percent of people with supported products were not using Apple Pay, according to a March survey. What's more, two-thirds of users reported checkout problems including slow or broken terminals and confused cashiers.
It's true that Apple Pay doesn't always work. The contactless mobile payment system at the CVS across the street has been down for months. Once I made the mistake of relying on Apple Pay to cover a taxi fare only to find the terminal in my cab wasn't working (luckily someone could meet me outside with cash).
There are also many places where Apple Pay is not accepted.
Still, Apple Pay is the market leader in contactless mobile payment (claiming two out of three dollars spent), and anyone who has seen it work will recognize this is the future.
Case in point, I found it astoundingly easy to buy headphones at the Apple Store this weekend. After talking over products with an associate, he offered to check me out on his phone. I've seen this before, though in the past I've handed the associate a credit card; in this case I asked (not recognizing any NFC/RFID box) if they accepted Apple Pay. The associate smiled: "We wouldn't be the Apple store if we didn't." I held out my phone, felt the buzz of an accepted payment, took the receipt by email, and was out the door a moment later.
I can't wait until every transaction is that easy.
Disclosure: I'm an Apple investor.