I've recently spent two days driving around in a Ford Transit van, putting boxes and bags into storage, and delivering some furniture to my godmother's house. The van was a stick shift, i.e. manual transmission, and my left arm feels like I've been stirring paint for hours.
The biggest problem with driving in London is the traffic, and the biggest problem with the traffic is having to creep forward two feet at a time, every time you're in a gridlock. Coming back from Walthamstow, about an hour's drive from my house, I hit the jam above on the M4 motorway, and was stuck in it for the next 30 minutes. Shift into 1st, creep forward two feet, back into neutral, repeat.
Every car I've every driven in the US was automatic, though I know manual does exist, because sneaky car manufacturers often quote their starting model prices with Manual, with automatic being an upgrade costing $1000-1500.
Needless to say our US cars will be automatic transmission.