My original idea was a list of the top 5 craft beers, but that is much too broad to make any sense. American craft beer is essentially all American beer minus the huge macro brewery rubbish. Every single brewer seems to have at least one version of almost every style you can imagine, and several styles that you couldn't begin to imagine that defy any category label. In order to do it justice, I would have to do a separate list for every single type. In time, maybe, but for now, it would be a good rule of thumb to list my top craft brewers, and trust that most of their offerings in every style will be top notch. Even with this short-cut list, there are going to be many deserving breweries that can't make the cut. Some of the smaller ones won't make it just because of the limited availability of their beers. This list could still have easily been a top 50 list. These brewers define what American beer is today. So, the first 5, then, in no particular order.
1. Dogfish Head
Out of Delaware and claiming to make off-centered ales for off-centered people, DFH regularly produces great beer, along with some of the most creative. Founder Sam Calagione has tended not to impress me with his personal style, but there is no arguing about his beer. I, admittedly, started out not wanting to like any of it, but love almost all of them. Their standard, 60-Minute IPA, is top of the line. You name it, they probably brew it. Not all are hits with me, and some are just crazy, but whatever version catches your attention, is probably worth a sample.
Taking almost the exact opposite philosophy to brewing as Dogfish, brewmaster Garrett Oliver is a traditionalist rather than mad scientist. There are plenty of great beer styles out there already that have been proven with the test of time, more effort into making those properly is all it should take. There's no need to go nuts trying to find some weird new beer, that may, or, much more often, may not work. Brooklyn's basic beers are true to style whether it is the Lager, Pilsner, IPA... They are all excellent and taste exactly like that beer should. No bells and whistles necessary.
A smaller brewery from Pennsylvania that boasts German trained brewers, but don't hold that against them. They do just fine with everything from their Belgian-style Golden Monkey to their almost over-the-top Hop Wallop. The closer the style gets to Germany, the more adept their hand, though. All of their various Pils are excellent, but their Belgians shouldn't be overlooked.
Probably best known for the Arrogant Bastard Ale, this California brewery doesn't mess around dumbing down the flavors to the masses. Most of their offerings are for real beer lovers that like just a bit extra. Extra hops, especially. The Ruination is probably the best of them, but I tend to appreciate the slightly more subtle ones, such as the Levitation, or Cali-Belgi. If you like your beers loud and obnoxious, these are, but still manage to retain the quality.
5. Flying Dog
I had to give a nod to the Dog from Maryland even though none of their individual beers are favorites of mine. Like Stone, they tend to be extremely flavorful beers, whatever the style. They have that gonzo-sensibility, and even use Hunter S. Thompson in their, rather far-fetched, backstory. In any case, they just can't be ignored. Almost always on any beer shelf, and more consistent than many brewers. These are always a good bet when you're looking for something with a bite.
While this list is, by definition, far from definitive, it is a solid sampling of the best beers brewed in America. No beer lover should have any trouble finding a favorite from among these brewers.