When it comes to small vendors there are those who use Square and everyone else.
Nearly every payment experience I've had with Square is one swipe, super fast, super simple.
Nearly every payment experience I've had with any other product is multiple swipes ... waiting ... waiting ... another swipe ... waiting ... failure ...swipe ... waiting ...
I can only guess the reason people use a Square competitor is to save a fraction of a % on commission.
The math is pretty simple: use a quality product that works, that will make your customers happy and will increase your throughput.