Well, what else can I say that hasn't been said already?
Just in case you haven't already been convinced, Borough Market is one of the most fabulous places on earth, and had I the time, money and location right I would shop there exclusively. I'm not sure you can get better quality or variety anywhere.
The Northfield Farm stall is a carnivore's paradise (the best bacon I've ever had, hands down). All other names escape me (I get too excited looking at the food to pay attention to the actual names, unfortunately) but you'll find unbelievable breads, jams, garlic and mushrooms at my favourite stalls.
If you really can't bear crowds, take a day off and head down on a Thursday or Friday. Ideal.