I like Williams Brewing a lot but they don't have a huge selection.
For my last purchase, I used YVH for the first time. I will probably use them more often because of their selection. If you are purchasing lower AA or noble hops, I would recommend emailing them to get the current value. I ordered some Tettnang that were only 2.1% and outside of their advertised range. That is not their fault however I would have made a different hop selection from other similar varieties which ended up being closer to 5% and would have been more useful for my purposes.
Both retailers are out West so that may not be ideal for you...