There are two great airports to fly into Southern California with. LAX, which is 45mins/1hr away from Orange County, and John Wayne Airport/SNA, which is in OC.
John Wayne Airport (SNA) Orange County
SNA pros and cons: You'll be right in the heart of Orange County and within 15-20 mins of the Church and Venue. Cheaper Uber from airport to local hotels and to wedding events. But your flight will likely be a bit more pricey and have less flight options.
Los Angeles International Airport
LAX pros and cons: There are more flights from more airlines at this massive international airport. You'll have a cheaper flight, but will probably have a longer / more expensive drive to the wedding location.
Can I get to Orange County from LAX by Train?
Yes! Amtrak has a $17 route between LA Union Station and Santa Ana (Orange County). Check the Amtrak departure times and compare with your arrival flight time before you buy your plane ticket to make there’s a scheduled train to get you out of LA.
The FlyAway Bus runs a 24 hour $9 shuttle service every half hour from LAX to LA Union Station where you can grab your Amtrak.