The Salisbury on Green Lanes is a great pub - best sausage and mash in London 2009. The pub quiz used to be really good but the Scottish guy left and now it's got quite a bit worse - but beers are still nice and the atmosphere is amazing. It's a basically intact Victorian pub. It was very grubby about 6-7 years ago, but they re-did it and this great Welsh guy bought the pub. Been great ever since.
The Crown near Liverpool Street is pretty good too - round the corner from the church on Cloudesley Square. It's a perfect summer pub, on a quiet residential street and a nice little outside section, perfect for a pint, a book and a cheeky smoke. Great beers too - and excellent pub food, probably the best all-round I've had (expensive though).
The Grand Union over the bridge from Westbourne Park tube is good too - they have another nice section right on the canal, as well as a good selection of beers and pretty good food. It's a bit out of the way though, it's out along the westway.