I'm gonna go with probably the most boring answer, and that's stretchy arms. Obviously super speed would be another obvious, boring answer, but that's not really the type of receiver I want my player to be. Being a receiver with arms that stretch indefinitely would be the ultimate cop out for any quarterback with accuracy problems, or quarterbacks who are just trying to throw the ball away. Receivers are often praised for having a huge "catch radius," where they can catch almost any ball that's thrown at them, whether its extremely contested or not, but with stretchy arms, one's catch radius would be infinite, and contesting a catch would almost be impossible. The only downside is that you'd still be able to drop the ball if the defender hit you hard enough in the chest, took your legs out, or tried to go for what bit of arm they could reach. All in all not the most overpowered super power, but still one that can be of great benefit for the offense.