If you are copying 35mm only then I would say that design would be best. There is a very long thread on here that shows a lot of different setups, you could have a look at that as well:
The Nikon setup has been around for a long time, particularly the ES-1 (for slides only), the ES-2 (for slides and negatives) came along much more recently. People seem to be liking the JJC ES-2 copy and more recently Valoi have produced their easy35. The easy35 allows you have some film rebate around your negatives, the others don’t, not important for slides in mounts of course.