I use Nikkor 60mm AF-S with Nikon ES-2 film holder on my D750 and it’s great. I prefer manual focus to autofocus; I never trust the autofocus so end up looking at each negative anyway; it’s easy to tweak focus with the AF-S. For a few dollars less you can get the 60mm AF-D lens which has the same optics but it’s just more clunky if you use autofocus then want to tweak it manually. If you just use it manually then no penalty. For either lens you can get perfect specimens from Ebay at substantial savings from new. The ES-2 should be cheaper than the negative supply holder. Then all you need is a tripod and a smooth LED light source for which there are good threads on this forum, I got the Chinese rectangular LED unit for about $50 and it works fine.
All of the above applies to 35mm. For 120, my Canon 9000F MkII scanner with VueScan works great. I’ve tried dslr scanning for 120 and it’s more work with no visible benefit.
My $.02