I could make a pretty good case for California. I could mention how the Sierra gets tons of snow (see Kirkwood or Sugar Bowl), maybe even how well the Sierra keeps snow (see Mammoth). I could let everybody in on a big secret about the quality of snow; epic windbuff, creamy corn, not too mention lots of deep pow, and how it sticks to very steep places, and how stable the snowpack is. I could bring up terrain, especially Mammoth, Squaw, Sugar Bowl, Alpine Etc... It might be worth mentioning some little known gems like Homewood, June, and Baldy. The Ca backcountry could be worth considering, with Tioga Pass, Bishop, Sonora, maybe even a little peak called Shasta that probably offers the best skiing in the US. Of course, I would NOT mention backcountry corn (call me selfish), and how it good it can be in May, June, even July. I could bring up the length of season, and how Boreal, Heavenly and Mammoth often open by Halloween, and how Mammoth often has great skiing on Independence Day. Some of us have seasons even longer than that(see backcountry). Some people like terrain parks, so I could talk about Mammoth, June, Squaw, Big Bear. I could talk about how easy it is to drive from LA to the local areas. These areas offer a surprising variety of skiing; steeps at Baldy/Waterman, amazing snow making at Summit and Bear, crusing at Snow Vally and Mt. High E, lift access BC at Waterman and Baldy, not to mention sunshine everywhere. On the same note, if we borrow Reno from the Silver State, we have a town with more nightlife than any ski town, a real airport, and great access to Lake Tahoe, and quite a bit closer to Mammoth/June than LA. I could talk about how Shane McConkey, CR Johnson, Jonny Moseley, Plake, Phils, Tanner, and a few hundred other pros choose the Sierra. A skier girl named "Kristi" was my neighbor last season, and she rented her condo from a snowboarder named "Tara". Yes, that Kristi. Did I mention sushine, and reasonable temps?
Oh well, I could say that I belive that CA has the best skiing in the USA, but I won't. I will just say that California (especially Mammoth) is my favorite place to ski.