If at all possible we fly into Long Beach Airport (LGB). It is a little further away from the resort than SNA, but much, much smaller and more convenient. There are only 10 gates at the airport and we've been known to exit the plane, have a potty break, get our luggage, pick up our rental car and be exiting the airport in 20 minutes! It probably takes 20 minutes just to get the luggage claim at LAX. SNA is a little better, but still bigger than LGB.
The main exit from the airport, Wardlow Rd., turns into Ball Road, which is the north end of the resort.
If you want to take a taxi, there's a fixed rate, that you have to ask for, from LGB to the Disneyland Resort area hotels.
In order of preference, I'd fly into LGB, SNA, and just cancel the trip if I have to fly into LAX. (OK, maybe that a little extreme, but I hate big airports.)