Neither...
I would recommend a third possibility... The Sigma 105mm f/2.8 OS USD Macro lens is a better value than either of the above.... currently on sale for $469 (reg. $969). That's almost $200 less than the Tamron and nearly half the price of the Micro-Nikkor.
According to this article, the Sigma 105mm also has much better image quality than the Micro-Nikkor 105mm:
https://petapixel.com/2020/04/15/macro-lens-test-canon-nikon-sony-laowa-sigma-and-tamron-compared/ Aside from image quality, the Sigma pretty much matches the Micro-Nikkor feature for feature. The Sigma might even have a more useful focus limiter and better image stabilization.
Frankly, I was surprised at the above lens test comparison. The Micro-Nikkor 105mm has near cult status reputation. I can't help but wonder if there was a problem with the example used in those tests. Most macro lenses from any manufacturer are better than that! OTOH, the Micro-Nikkor 105mm is one of the oldest designs in that comparison. (The Sony and Canon lenses in article are only useful for comparison sake, since neither can be used on a Nikon F-mount camera.)
I use Canon gear, including their earlier EF 100mm f/2.8 USM macro lens (not the newer L/IS version). Other macro I use include the Tamron 60mm f/2 (crop only); a vintage, manual focus only Tamron SP 90mm; Canon 180mm f/3.5L USM macro, and TS-E 45mm f/2.8 Tilt-Shift (for small product photography... I've also used the TS-E 90mm f/2.8 in the past, but don't currently have one). I use a number of macro extension tubes to do close-ups with a variety of other, non-macro lenses, too.
If I were shopping for a macro lens today, the Sigma 105mm OS HSM would be right at the top of my list!
Neither... br br I would recommend a third possib... (