I don't know if i ever had a single beer that enabled that a-ha moment, i guess the closest would be guinness. My grandfather was renowned for his love of cheap beers like Olympia, Ballantine, Schaefer, etc so i grew up sipping those.
I did join a 101 beer club at a local sportsbar and had a ton of great beers, i guess that's what really got me into it. plus, the black satin jacket i got for drinking the 101st beer was damn sexy.