Paypal are "winning" and will forever "win" because they support EVERYONE. Finding a person who can't use Paypal (who is over the age of 18 and isn't a previously terminated customer) is very hard because it supports (almost) EVERYONE yet these "new" "paypal killers" don't and they won't gain any traction because of this.
and even then there are still bigger issues, but the biggest issue is international support.