To be honest, none. For typical studio work, you are best off with (ideally leaf shutter medium format) SLRs, or, for pack shot/still-life, with view cameras (or a DSLR with shift-tilt lens). Most rangefinders have visible parallax and/or frame scaling issues at close distance. The Fuji G(S)W series medium format rangefinders are about as good as it gets, but even these are no primary choice for studio work.
In other words: Use of rangefinders in studio can be done - and has sometimes been done - when no better tool is at hand, or when the most suitable lens for a desired/required look only comes in rangefinder mount. But in most cases, any of SLR, EVIL or view camera would be preferable - and if rangefinder, you'd want a M8, M9 or R-D1 to be able to chimp.
Of course, there are subjects sometimes shot in studios that aren't particularly studio associated, and for these, rangefinders will be just as suitable as they'd be elsewhere.
Leaf shutter cameras have the advantage of shorter flash sync times - as sometimes necessary to cut out ambient light - but that is more of a outdoor strobist than a studio requirement.