Assuming that there are no pickup routs then, as @Paul S says, go for what appeals to you aesthetically and physically. If there are existing routs, however, a SS body will effectively move the pickups towards the neck leading a slightly more ‘plummier’, whereas a LS body will add a slightly more mid range focus to the sound.*
*I’m imagining these scenarios without getting out of my chair and looking at a bass and I think I have it the right way round, either way, if the routs are already there, there will be a tonal aspect to consider too.