The right side is the best.

The normal flight path takes you over water for most of the trip. The plane crosses over land at Santa Monica, heading east, and then makes a 180 directly over downtown, heading back toward the ocean.

From 2D you'd be able to see the sunset (if your flight is timed right of course). Once over the L.A. basin, first you get a view to the south, which includes LAX, Palos Verdes, Long Beach. Then as the plane banks and turns, you can see the skyscraper cluster downtown, USC, the Union Pacific railyards. Then on final approach, the view north yields downtown, Hollywood, the skyscraper clusters of Century City and Westwood.

L.A. at night is stunningly breathtaking, and a flight approach like this is the most excellent way to see it.

OT, with this approach the plane usually lands on the north side of the airport (24L/R), which means a long 10-15 minute taxi to the gate. On Channel 9 you can sometimes hear the pilot try and negotiate with air traffic control for 25L/R, in which case the taxi time is 2 or 3 minutes.