I've lived all over the United States in most of the Big Cities my bud ranking is a follows

#1 San Francisco (and many other California cities apply as well) - It might have helped that I was living with Denis Peron
#2 Seattle - Lots of good stuff there
#3 NYC - The ranking would be higher but a lot of shady shit goes on there and quality weed can sometimes cost ya an arm and a leg.
#4 Boston - It probably came from Vermont or the MIT science freaks. Better prices than most places.
#5 Chicago - Good stuff can be found but prices were very sporadic for me.

ok so the Worst...

Phoenix