This Top Ten Porters list is from America's Best and Top Ten and from the results of the 2009 US Open Beer Championship.
 
1. Black Butte Porter, Deschutes Brewing - Oregon
2. Big Dog Porter, Neustadt Springs Brewery - Canada
3. Sierra Nevada Porter, Sierra Nevada Brewing - California
4. Shipyard Imperial Porter  - Shipyard Brewing - Maine
5. Meantime London Porter - Meantime Brewing Company - England
6. Arcadia London Porter - Arcadia Brewing - Michigan
7. Benchwarmer Porter - Cooperstown Brewing - New York
8. Entire Butt English Porter - Salopian Brewing - England
9. Geary's London Style Porter - Geary's Brewing - Maine
10. Longfellow Winter Ale - Shipyard Brewing - Maine
  

    
Brown Porters
Brown porters are mid to dark brown in color. No roast barley or strong burnt/black malt character should be perceived. Low to medium malt sweetness is acceptable along with medium hop bitterness. This is a light- to medium-bodied beer. Fruity esters are acceptable. Hop flavor and aroma may vary from being negligible to medium in character.
Statistics:
OG: 1.040 – 1.052
FG: 1.008 – 1.014
IBUs: 18 – 35
SRM: 20 – 30
ABV: 4 – 5.4%
 

Robust Porter
Robust porters are black in color and have a roast malt flavor but no roast barley flavor. These porters have a sharp bitterness of black malt without a highly burnt/charcoal flavor. Robust porters range from medium to full in body and have a malty sweetness. Hop bitterness is medium to high, with hop aroma and flavor ranging from negligible to medium. Diacetyl is not acceptable. Fruity esters should be evident, balanced with roast malt and hop bitterness.
Statistics:
OG: 1.045-1.060
FG: 1.008-1.016
IBU: 25-40
SRM: 30+
ABV: 5.0-6.5%