There was a big poll done for this with 192 beer geeks voting. The majority concensus was extremely close in votes, but for poll purposes, (in order):
Centennial
Amarillo
Simcoe
Citra and Cascade were the runners up.
Columbus nearby.
I personally love Simcoe and Columbus. These are the main hops used in both Heady and Pliny... And many more top rated IIPAs. Supporting hop choice to this combo doesn't really matter as long as it's a Pacific NW IPA hop.
So many great new hops about, citra, mosaic, nelson sauvin, which area great, but I find myself craving good old 'Murican 'C' hops in a west coast IPA.
My favorites are Centennial and Citra. Don't have a third right now, I've used Galaxy, Nugget, and Galena with good results. Working on an IPA with honey malt that may help me develop a strong third, but for now I only have two.