If you're a craft beer connoisseur, there are certain beers that were likely your gateway into the world of craft beer. You may not have known it at the time, but once you tasted them, your palate realized that, yes, beer can be something different than what's being sold as beer on clever tv commercials. If you came of drinking age in the 1990s, I think the following three beers, which I consider the "classics," were likely part of your craft beer introduction:
Sierra Nevada Pale Ale: The classic pale ale that was likely my introduction to craft beer back in the '90s. It still doesn't disappoint. In terms of flavor, it may have been surpassed by others over the years, but this one is the grandfather of them all.
Samuel Adams Boston Lager: Possibly the most pervasive craft beer in America (Blue Moon doesn't count). If you're into craft beer, it's easy to overlook, but it's still worth coming back to now and again. At many dining establishments, this might be your only craft choice. My review here.
Anchor Steam Beer: It took me a long time to realize that the brewery is "Anchor" and the beer style is "Steam," rather than "Anchor Steam" being the brewery name (which would be a cool name for a brewery). "Steam" beer is an old American style that's not widely brewed anymore, and everyone but Anchor has to call it "California Common," as Anchor holds the rights to the designation "steam beer" (more info here). Anchor Steam has a distinct, even unique taste. Malty, with hops, bread, and touches of caramel and citrus, and even what I call a slight cotton candy touch at the front.
The best thing about each of these beers is not only are they tasty, but they're affordable and widely available.