Burbank is great, too. Getting to and from LAX isn't the problem, it's getting around the airport that is the real headache. All rental cars are way offsite and without an express service (Emerald Aisle) the lines at rental counters are unbearable (so are the rental car exit stations).
SNA>LGB>ONT or BUR>...............>LAX.
LGB is serviced by Alaska, AmericaWest, American, and JetBlue, so there are quite a lot of options considering code-shares.
Fares are the real equalizer, but LAX has some of the highest PFC's anywhere. Sometimes you can save a ton on rental car fees by picking up at one airport and returning at another in the same metro area.