As far as lenses go, I say test samples of as many lenses that you can afford, rent, or borrow. Over the years have used many macro lenses. Once had a 60mm f/2.8 Leitz Wetzlar Macro Elmarit lens that was a dog when copying flat copy. Then another time was commissioned to photograph a series of very rare circa 1860 topographical drawings. Had to use the Museum's copy stand (with 2 lights that I brought in), under their constant supervision. Needed to use a WA lens to be able to cover the drawings with one exposure each per their demands, long story... Anyways tested all the lenses that I had or was able to borrow at the time and amazingly to me, the one that performed absolutely the best was my first generation 20-35mm f/3.5 AF Nikkor. For shooting my LF negatives (use a D850), settled on a 120mm f/6.3 Macro Nikkor off of my Nikon Multiphot. Side by side it blew away any of the conventional macro lenses that I could test. Lens is stopped down one f/stop from wide open. Illumination very even across the FX format. Lens was designed to photograph flat specimens. My greatest challenge was finding a "perfectly" even lightbox/panel. Who knows maybe in 2020 will be able to justify acquiring an Epson Expression 12000XL.