What you can get depends a lot on where you are, but as a rule of thumb you'll get find a lot more pleasant surprises looking amongst smaller local or regional fare than big national or global brands.
I've got to agree with
Lord Blackadder above, the best thing you can do for yourself is sample broadly. You'll likely find favorites few if any of us have ever heard of. Again, your ability to do this depends heavily on where you are. If there is a Whole Foods near you they tend to carry a fair selection, though I've found it varies greatly from time to time and store to store. Over the holidays "Cost Plus World Market" stores had a couple of variety boxes of fairly good beers available even in smaller markets.
If nothing like that is nearby, your best bet may actually require some scouting to find the right hole in the wall establishment, liquor or convenience store, where the owner just happens to be a beer fanatic.
As for my own preferences, I'm enormously partial to American IPAs. If there's a beer that's too hoppy, I haven't found it. Right now my refrigerator houses some
Speakeasy Double Daddy and some
Stone Oaked Arrogant Bastard. Once those are gone, probably it'll be something else though. Well, maybe some more of the Stone. It's some tasty beer.
If you're particularly looking for something dark and you can find it, you might try
Stone Smoked Porter, but I was only reminded specifically of it because I was on the site already. It's pretty good, but the best porter I ever had came from a local microbrewery, being strong and smoky in a way that made it taste of bacon. There's just no way that can be bad.