I am really getting interested in what the OP is going to think of the experience.
On like-for-like flights, it seems a no brainer to choose EK, but if he is (for instance) based in the UK and has regular travel to the (for instance) USA, the route network will (to say it nicely) not be optimal. And (in that case) the EK lounge experience at LHR will be inferior to the Concorde Room (or so I believe, I have never entered that 'hallowed ground' ). Except for the boarding from the lounge benefit of course.
Feedback will be interesting!