My favorite app is easily Venmo. My friends never have an excuse to not pay me back. Then vis versa, I am able to pay anyone immediately. It is just so convenient especially since almost no one uses cash anymore.
My mom will send me money through Venmo randomly, and those are the best days ever. I pay my nail lady through Venmo, I travel often and it is so easy to split a trip among friends with the app. You also usually know when someone is going to Venmo you, but still when it happens it’s like a personal payday. It’s probably my favorite because it is my most used, and there is an actual point and reason to using it. It also is really simple and easy to use, like if my mom can do it then you can do it too.