There are really only 2 reasons to use cantilever brakes;

1. Your using drop handlebars with short pull brake levers. Even in this case it's probably better to use a travel agent and use linear pull brakes (V-brakes).

2. Your into the retro-look thing, fashion. Nothing wrong with this reason unless you are a heavy person or have a heavily loaded bike where safety really should prevail.

Linear pull brakes out perform Canti's in every category. Get the Shimano parallel pull models and have the best in braking, equal to most disc brakes. The heavier you and your bike are, the more important brake selection is.