I think the fastest elevator path out of the beginning four characters is The Marine's path because if you can get each room done fast enough you can get to the boss pretty quickly. But in my opinion The Convict's path is the easiest to complete without taking any damage but it probably one of the slowest paths you can pick. Do NOT pick The Hunter's path, it is one of the hardest paths and it's not any faster than The Convicts, you'd be better off just picking another path or playing another character all together.