A lot may depend on factors like the lenses you actually have in hand for the formats you are shooting, and I wouldn't discount grain as a factor in what the final print is going to look like.

One thing to be aware of, if you've got a really good macro lens for 35mm is that it will cover larger formats at larger magnification, if you can find a way to mount it physically to the camera. At the same time, it may be the case that the lens is better optimized for the magnification ratios likely encountered with the primary format than with the format the lens has been adapted to (say 1x-5x on 35mm could be better than 8x-40x on 8x10").

Just run some tests and make some prints with what you have, and you'll see what you like. When I've had a particular macro project, that's what I've done, trying different lenses, reversed lenses, enlarging lenses, etc. at different reproduction ratios, and seeing what works. If you have a real macro lens for 35mm, it may look better than a non-macro lens for 4x5", at macro magnifications. You may find, for instance, that a lens that isn't a dedicated macro lens for the magnification ratio at hand introduces an unexpected distortion or an internal reflection or flare (adequately shading a reversed lens can be tricky) that produces a hot spot, negating any other advantage of the lens.