Flagship beers by style

Samuel Smith's Oatmeal Stout

 

Weihenstephaner Hefe Weissbier. I love that it's both the most AND the highest rated for its style. You almost never see that. Ayinger Celebrator is the only other one I can think of that fits that description.

Sierra Nevada Pale Ale
Pilsner Urquell
Westmalle Tripel

 

I try to accomplish something like what you're doing by searching out the beers at the top of the style lists. I figure if a beer has been reviewed a few thousand times it must be a decent representative of the style.

 

American Pale Ale- Sierra Nevada Pale Ale.

California Common/Steam Beer- Anchor Steam

Barrel Aged Stout- Bourbon County (this might be arguable)

 

I personally think Ayinger's Marzen/Oktoberfest belongs on this list.

 

For IPAs/DIPAs, I'd say Fat Head's Head Hunter and Dogfish Head 90 minute

 

IPAs/DIPAS: Celebration, Hop Devil, Hopslam
APAs/DAPAs: Anchor Liberty
Saisons: DuPont
Belgians: Hard to say...to vast a category
Sours/funks:
Stouts: Brooklyn Chocolate
Pilsners: Jever
Kolschs: Gaffel
Scottish Ales: Skullsplitter
Wheats: Aventinus, Winter Cheers (not tried and true, but simply awesome and distinct)
Fruits: Abita Strawberry Harvest (yep, I said that) and Blue Point Blueberry Ale (yes, I said that too)
Holiday beers: Shiner Cheers (yes, food coloring and all), St. Bernardus, Old Fezzi, Cold Mountain (my favorite)

 

Reissdorf Kolsch

 

Saison: Dupont is a clear favorite I would say. Personal preference is Boulevard Saison Brett.

 

I don't think it really answers the question to give the "best" of each style. A flagship of a style or a representative example of a style should be something with historical significance, relative accessibility (when possible), and quality. I tried to include beers that most people can get relatively easily and are "classics."

Even if you're not a fan of SNPA, there's no doubt it's the flagship of the American pale ales.
IPA should be RR Blind Pig, Stone IPA, Bells Two-Hearted, or SN Celebration
IIPA is RR Pliny.
BCBS is unquestionably the BA stout representative too.
Porter I'd go with Great Lakes Edmund Fitzgerald, Founders Porter, or Sam Smith Taddy Porter
Sierra Nevada Stout or Deschutes Obsidian for regular stout.
Russian imperial stout is North Coast Old Rasputin or Sam Smith Imperial stout
Coffee stout is Alesmith Speedway or Founders Breakfast Stout.
American imperial stout is Victory Storm King
Milk Stout is Left Hand Milk Stout Nitro
Mexican stout is Perennial Abraxas, Cigar City Hunahpu, Prairie Bomb!, or Westbrook Mexican Cake
Doppelbock is Ayinger Celebrator.
Weihenstephaner Hefe is hefeweizen (and their Kristall is probably the kristallweizen representative too).
Czech Pilsner is Pilsner Urquell or GLBC The Wright Pils.
German Pilsner is Bitburger Pils, Prima Pils, or NG Hometown Blonde
Marzen is Ayinger
Belgian Quad is either Rochefort 10 or Westvleteren XII.
Westmalle Tripel for tripel
Witbier is St. Bernsrdus Witbier, Hoegaarden, or Allagash White
For Rauchbier pick an Aecht-Schlenkerla
Vienna Lager is GLBC Eliot Ness or Sam Adams Boston Lager
Duvel is Belgian strong pale ale
English Barleywine is FW Sucaba or JW Lee's Harvest
American Barleywine is SN Bigfoot.
Old Ale is Thomas Hardy but HotD Adam from the Wood would work if you can't find Hardy.

I think you need to differentiate the different styles of "sours/funks," since that's not really a style and it would be an incredibly broad category.
Gose should be Ritterguts or Leipziger (or Westbrook if you're feeling patriotic)
Gueuze should be Drie Fonteinen Oude Gueuze.
For fruit lambic, pick a Cantillon (I'm partial to Fou or St. Lam).
American Wild is tough because it's huge, but maybe RR Beatification or NB Le Terroir
Flanders Red is easy: Rodenbach Grand Cru
Flanders Oud Bruin is harder, but I'd go with Petrus Aged Pale or NB La Folie.
Saison DuPont is the quintessential saison.
Berliner Weiss may be New Glarus, Bruery Hottenroth, or (despite rarity) De Garde Bu Weiss. Perhaps someone knows an actual German example more worthy of being here.
Fruit beer is any New Glarus fruit.

 

IPA: Stone IPA
IIPA: Pliny
Saison: Dupont
Tripel: La Fin du Monde or Westmalle
Wit: Hoegaarden
Vienna Lager: Sam Adams Boston Lager
Belgian: Duvel
Barleywine: Sucaba
Porter: Black Butte
American Stout: Sierra Nevada
Russian Imperial Stout: Old Raspy
Pilsner: Urquell and Bitburger
Schwarzbier: Kostritzer

 

I forgot one that's really obvious: Orval for Belgian Pale Ale.

 

IPA-Bell's Two Hearted
DIPA-Bell's Hopslam
APA-Three Floyds Zombie Dust
Imp. Stout-FBS
Christmas Ale-Great Lakes Christmas Ale
Porter-Great Lakes Edmund Fitzgerald