Sounds like you've been to them all so you're a good person to ask.
When I was an avid skier I didn't really go to that many different ski resorts. China was close... it was good, if not great... and that's where I went the majority of the time.
I have skied the Tahoe area... NOT Squaw Valley... but I have skied Incline, Heavenly, Kirkwood, Northstar... couple others that I forget. BUT... only ONE trip to each of those... maybe two to Kirkwood.
Out of state I've skied very few... but my favorite was Taos... in fact Taos I believe is my favorite over all.
Out of country I skied several but I can't remember the names for any of them... couple in Germany, couple in Switzerland, I think 3 in Italy. Problem is that with almost all those European ski trips is that it was during, or near, summer and it was glacier skiing... I don't like glacier skiing, much anyway.
So anyway... give me two.. your favorite in California and then your favorite 'wherever'. - JamesJM