CockneyRebel.
1) I'm used to it
2) When I see a double-decker, I don't want to think "Ooo, a Routemaster! Routemaster likes Routemasters!", I'd rather think "Cockney likes Routemasters!"
3) CockneyRebel sounds better. The avatar shows your obsession pretty well.
_________________
I was sad when I found that she left
But then I found
That I could speak to her,
In a way
And sadness turned to comfort
We all go there