John Wayne is a much closer airport.
I do agree that LAX can be overcrowded and extremely busy at times. It's a major airport, that was built on cheap land, and was surrounded before a decent expansion could happen.
Besides, Ontario is a wonderfully quick airport. I greatly prefer it to LAX which takes a good thirty minutes just to get in and out of - if you're lucky.
Not many direct flights to Ontario compaired to LAX. If they offered a free shuttle to and from Disneyland, and free tickets, then I would consider it