Which aviation GPS is more common?

Me and one of my co-workers were having a discussion about GPS's the other day and we've come to a disagreement. From what I understand, Garmin is the most common GPS used in the aviation industry and my co-worker thinks that Magellan is. Does anybody on here happen to know? I'm pretty sure I'm right since I've talked to pilots before and I want to rub it in his face since he tends to be rather uppity about what he thinks he's right about.