I would recommend Sunrise
Hi--
I completed the Basic Aerobatic course at Sunrise in 1992 in the Decathalon. I would highly recommend this school.
They take training very seriously and are priced competitively.
I'm sure there are other good schools out there but I know Sunrise is one of the best. They often compete in aerobatic competitions.
The only problem in the Orange County area is congested airspace mixed with (sometimes) low visibility due to pollution and moisture from the ocean.
Have fun!