If you visit York again, try and get to the Ebor in Bishopthorpe, it is the only remaining SS tenant pub in the country and is excellent, very different to all other SS pubs as they can do things and sell products that other SS pubs cannot do.
Regarding quality of beer, The Trafalgar is a bit of a "back street" rough pub, but the manager there does look after his beer very well and serves a perfect pint of OBB, I always make a point of having a couple of beers in that place when I am having a crawl around town.
Regarding other posts, I have to agree that the Blacksmiths Arms (just down the road from me) is very good now, I have only visited once very recently, but the OBB was spot on when I did visit, locals quite pleasant too.
I am confused with the Kings Arms, which is quite a famous and well known pub in York as it always gets flooded but still tries to remain open, they even have the various electricity cables ran high up in the walls to remain open during floods. But they do not serve cask OBB? I went in and went straight back out last summer as a result.
Burns, quite good, is always busy but a decent pint, good location as in the town centre.
York Arms, again a decent pint and York centre, landlady was very good and chatty last time I went in.
Brigadier Gerard, very chavy, crap un-kept beer, rude staff, don't bust a gut trying to visit that pub.