I've just bought a Brompton for a similar commute in London, and so far am very happy with it. The fold is small and well-engineered, and the ride is good. (Although I did need to put a jubilee clip around the rear suspension block, to stiffen it up a bit)

I've not got the luggage, although the received wisdom is that it's great.

I did look at the others: Airnimals are wonderful, but aren't folders in the traditional sense - more like 'can be packaged up in a suitcase in 5 minutes'. The Birdys and Dahons have more cumbersome packages, and although you get more gears, London is still pretty flat. 2 gears are doing me nicely.