My first beer experience was Milwaukee's Best.
My first good beer experience was Sam Adams Boston Lager, which tasted so different from Coors and Bud I initially didn't like it. Took me three days to finish the six-pack, but after day 3 I could never go back to the likes of Coors and Bud again.
My first craft beer experience, a life changer, was Sierra Nevada Torpedo IPA, and Arrogant Bastard. Because of those every beer must be full and flavorful now.