Sorry James, I can't agree on your points supporting LHR.
1. The terminal is brand new
Nice, but not nearly enough of a reason to make me put up with everything else involved with routing through LHR.
2. Access to 4 *A lounges at the airport (AC,UA,SQ,LH) whilst flying in Y some of which are miles ahead of the Number 1 and similar lounges found at LGW
Couldn't care less since (1) *A network is of little interest to me (and I would venture, many other WS pax), and (2) London is inevitably a destination and not a connection, so I'm in and out of the airport as quickly as possible. Personally speaking, I try to avoid spending any more time in airports than absolutely necessary. Unless you're forced to wait out a longer connection, hanging out at the lounge seems a terrible waste of time.
3. Access to fast-track security whilst flying in Y
Never had an issue getting through either security or customs at LGW. Not even once.
4. Speedy immigration starting this Summer when Border Force opens the eGates to Canucks, Yankees, Ozzies and Kiwis
See above. Never been an issue at LGW.
5. Complimentary upgrade to First Class on Heathrow Express
Fine, if you need to go to Paddington. Victoria is far more convenient for me, so it's Gatwick Express every time. Downtown in 25 minutes.
6. Cheap travel from central London to Heathrow on the Jubilee line.
See above.
Hey man, to each their own. There are plenty of existing options to LHR. I appreciate being able to avoid all of that. Westjet ... please .... don't even think of changing!