Assuming I had my keys, wallet, and credit cards already secured, my choice would also be my laptop. But it wouldn't be a disaster if I left it behind.
It's critical for me to have access to my business data, so I have my entire home directory under version control (currently mercurial, soon switching to git). On any given day I make several commits and push out all changes. I usually have my encrypted data residing in no fewer than two (and usually three) different geographical locations.
The main reason I would grab the laptop would be to avoid the hassle of pulling back in all the remote data, which might require a few hours, depending on the speed of the network connection. All of my configuration files are under version control, so re-establishing my work development environment doesn't take long.
A more likely scenario than a burning building would be a crashed drive, though hard drives (or maybe filesystems?) have become incredibly reliable in recent years.