Normally I would pick the bigger one. What shaper do you have?
A shaper can usually take some hefty roughing cuts and easily deals with tough jobs a lathe would hate, hence the bigger the better in most circumstances
You can also make your own vices on a shaper because they excel at flat surfaces, a solid steel vice can last a lifetime
Edited By Ady1 on 29/01/2016 11:42:25