Of course the Micro Nikkor is the lens to use for serious macro. If the OP wants a lens for regular shooting, the 105/2.5 Nikkor is a legendary lens in that focal length which I believe will outperform the Tamron 90/2.5 macro at or near infinity. All I did was point out that there is one way the 105 f/4 is not equal to the 2.5. I would expect the 2.5 to be better than the f/4 at or near infinity, especially at apertures between f4 and f2.5.
My earlier posts in this thread make my opinions clear.