Originally Posted by Mwenenzi

1 = National Express coach
2 = National Express coach or Uber/pre booked taxi. Not a lot of difference
3 = Uber/pre booked taxi.
7 = Contact a limo/minibus service. May get 1 vehicle. but may depend on your baggage.

Are several threads on LHR<--->LGW transfers. A common question.
https://www.flyertalk.com/forum/u-k-ireland-484/
UK & Ireland Dashboard: London Airport Transfers, Rail, Eurostar & Destination Guides