If you could only drink one commercial beer for the rest of your life.......

[Stevieboy]

mine would be (I think) Guinness Original

 

[Tess Tickle's Brewery]

Heavy Pop by Overtone!

 

[jceg316]

If we're assuming we're getting the best possible quality version available I'd go for Staropramen. Drinking it at the brewing in Prague was one of the best beers I've had in my life.

If we're going by the best beers we can get currently now (Prague is a bit far from South London) I'd probably say Fruh.

 

[moto748]

On draught: Guinness

In bottle/can: Black Sheep

 

[Cheshire Cat]

Summer Lightning

 

[Cwrex]

Guinness too

 

[JonBrew]

Duvel

 

[An Ankoù]

Summer Lightning

Me too.

 

[Horners]

Old Peculier

 

[RichK]

Otter Ale

 

[Little Rock Brewing]

La Chouffe.

 

[Guzzie]

Jever

 

[devexwarrior]

Doom Bar or London Pride

 

[Stevieboy]

Doom Bar or London Pride

London Pride was on my list too.

 

[AnimatedGIF]

Brickworks Bitter from Bingham's brewery. Just lovely, especially from cask. And it's local.

 

[Rodcx500z]

Proper job or JW Lees moonraker

 

[Stu's Brews]

If we aren't including craft breweries in the 'commercial' tag then I'd probably go for Proper Job. Otherwise, I think it would be Wild IPA by Wild Beer

 

[Chippy_Tea]

I am with @Horners its Old Peculier for me -

 

[jayk34]

West Indies porter

 

[Covrich]

Old perculiar or Crafty old hen