Sainsbury'si have four bottled stouts in their stores at the mo. Guinnessi Foreign Stout (7.5%), Guinness Regular (4.2%), O'Hanlon's Port Stout (4.8%) & Titanic Stout (4.5%). I didn't bother with the Guinness Foreign Stout for comparison purposes as the high alcohol strength makes it stand out a mile and means its not a session beer.
Rhian guessed the Guinness straight away and it was her favourite, but thought that the Titanic was smoother than O'Hanlon's. I preferred O'Hanlon's overall.
I'd never considered how much burnt black malt flavour is in the Titanic Stout until I compared it directly with the others. The O'Hanlon's is very smooth and the Guinness is the stereotypical stout flavour that springs to mind when you think of the style. My order of preference: O'Hanlon's, Guinness, Titanic.
All good stuff though!