I have a few depending on the category of beer:
Stout:
Three Floyd's Dark Lord Imperial Stout is a a hands down favorite for me, especially if you age it for a couple of months/year.
Dark Lord Imperial Stout - Three Floyds Brewing Co. & Brewpub - Munster, IN - BeerAdvocate
Pale Ales:
Depending on what you can get your hands on regionally there are a few that are pretty nice.
If you are out west, Russian River Brewery's Pliny the Elder is a pretty nice hoppy ale.
Pliny The Elder - Russian River Brewing Company - Santa Rosa, CA - BeerAdvocate
A little more common to Midwesterners is Zombie Dust by Three Floyd's out in Indiana. It has spotty availability but is an amazing citrusy and hoppy spa.
Zombie Dust - Three Floyds Brewing Co. & Brewpub - Munster, IN - BeerAdvocate
More common than the two above but still rare in its own right due to being seasonal and people buying it like it's crack i'd prolly recommend Dogfish Head's 120 min IPA. It may be overkill for some palettes(at about 120 ibu so it'll be bitter)but still worth a check.
120 Minute IPA - Dogfish Head Brewery - Milton, DE - BeerAdvocate
Barleywines:
This is my personal favorite area. My hands down favorite in the category would be something like Firestone Walker Succaba Barleywine. If you get a chance to try it out or get a bottle jump on it! or Hell PM me and I'll buy it off of you.
§ucaba (Abacus) - Firestone Walker Brewing Co. - Paso Robles, CA - BeerAdvocate
A little easier to find and still very enjoyable would be something like Weyerbacher's Insanity to at least give you a taste of what you could expect out of the category.
Insanity - Weyerbacher Brewing Co. - Easton, PA - BeerAdvocate
Hope this helps!