I have three folding bikes: Dahon, Bike Friday, and Brompton. Dahon is good because you do not need to worry much about someone stealing it, and I have the option to fold it and carry it to another place. However, folding and carrying are cumbersome and should be done in rare cases. Bike Friday rides nicely. Its folding is even more cumbersome than Dahon's, and carrying it is impossible. You can disassemble it and put it into a suitcase, where it fits better than Dahon. To take Dahon on air travel, I needed to put it into 2 suitcases. Brompton folds in seconds, and you put it into a travel case in minutes. It is relatively easy to carry around. It does not ride as nicely as Bike Friday, but I commute on it to my work 5 miles away daily. If I were allowed to retain only one folder, it would have been Brompton. If I were to retain just one bike of any sort, I would hesitate, but there is a high chance that I would take the Brompton because it gives me the most options to ride.