if in L.A., mammoth is the closest really good mountain (world class), but, unfortunately, everybody in L.A. knows it. Mammoth is also huge, about 6 times bigger than anything in L.A. and has tons and tons of real snow (any snow is rare at L.A. resorts).
Sierra Summit is a little closer than mammoth, but only about 25% larger than L.A. resorts (combining bear/snow summit or all of mt. high). Good thing is Sierra Summit gets about 75% of the snow mammoth gets (a ton) and very few L.A. residents choose it over mammoth, so it's usually uncrowded. I live near Fresno and ride Sierra Summit a lot, too.