In a perfect world, you wouldn't have to eat any steak other than dry-aged USDA Prime beef. The reality is that even most restaurants don't serve beef of this quality. Even those who claim "prime" beef probably aren't serving actual USDA Prime. and those restaurants making claims of "aged", well guess what: it's probably not dry-aged, but rather wet-aged, which is cheaper process that doesn't come close to the same results of dry-aging. If you have any doubt in your mind about that, buy two steaks: a dry-aged steak and a wet-aged steak, and smell them both. The wet-aged will smell like nothing. the dry-aged will smell like the nastiest filthiest piece of meat that you've ever smelled short of a dumpster. And that means it's friggin' good. That, in short, is what you want.
My go-to market for dry-aged
Prime Choice (they no longer dry-age Prime, maddeningly) beef is Whole Foods . They usually do a pretty good job, and claim to sell USDA Prime (but they don't dry-aged it). It's important to understand that even though Prime is the best of the best, within the grading of Prime there exist different levels. All Prime is not equal. As you can see in the above photo, tonight's steak didn't have the close-to-perfect marbling that i'd expect from best-of-the-best Prime. You win some and you lose some. What that steak did have going for it, however, is that I had the butcher cut a special piece for me, 1.5 inches thick (an optimal thickness in my mind), and he took it from the end. And that steak at the end of the big ol' piece of beef in the fridge is the nastiest, purplest, smelliest piece of the lot. And that's there's some good steak.
I try to duplicate the steakhouse (meaning: Peter Luger's, Wolfgang's, Ben and Jack's in NYC) experience (meaning: good crust, rare inside) by using an outdoor (gas) grill at top-top heat. I also drizzle some olive oil on the steak so that any drippings cause some flairups (and cancer if you listen to what "they" say). In 7 minutes (more or less), the steak is a perfect medium rare. Tent and rest for 5 minutes, and you're all set.