If you are going to DEL from SAN then take the AA flights. I've flown to India using all three of the methods you suggest plus a lot more and the AA flight is the easiest.

You don't want to fly through LHR to anywhere due to the carry on restrictions plus you would have to connect twice in both directions. Do you want to get into DEL at 1:25AM? Do you want to depart DEL at 3:25 AM? The CX connections are not great either. The CX flight lands at 2:15 AM with 2 connections and a rather long layover in HKG. It departs DEL at 7:40 AM which may seem reasonable, but you often need to be at the DEL airport 3 or 4 hours before the flight which means you are going to need to leave your hotel at 3 or 4 in the morning.

Using the VIPs on that flight is not hard. My success has been 100%. Get on the waitlist.