Id pick the stock you like best. If its without a chassis shoot it first and see how it goes, if you feel it isnt shooting up to par then either send it out to be bedded or bed it yourself if you have some confidence. Buy it with pillars pre-installed , if you end up getting it bedded they can either use them or punch them out and use bigger ones if that's their practice. If you bed it you wont have to worry about pillars.
Also, not all actions fit the mini chassis perfect, couple of threads have popped up that require a rear pillar installed and some have bedded lugs or full actions also. Not the majority but still also a possibility pending your action and its fit with the chassis.
Me personally i prefer the feeling of a mcmillan, just fits me better and feels better. Also a 1 to 1 bedded fit will in my mind always be better than a chassis intended to fit all. If you plan on moving the stock around to different barreled actions a bedded fit is not the best choice, leave it bare or go chassis. Cant go wrong with either honestly they both perform excellent.