Ice hockey. Sure, they tend a much smaller net, but their reaction speeds are off the charts. A childhood mate of mine was signed to Hull Vikings when he was about 17/8 or so, also on the books at Hull FC briefly, proper Billy Sport he was, but he wasn't much for football - much like a lot of young lads in Hull aren't or weren't at that time, it's very much a rugby league City.
Anyway, whenever we'd have a kickabout in the park on the Sunday league pitches, or even just play heads and volleys against a shop wall, he'd always go in goal being he was a hockey keeper and I swear on my life it was almost impossible to get the ball past him at times. He wasn't the tallest lad, about 6'0" dead on, as well as being a unit width wise like most rubgy lads, but he was like a cat. To this day I genuinely think he could have made a decent career out of football if he'd gone to a few keeper trials and tryouts. He was all about the contact sports though.