"At infinity resolution drops fast when measured out of a 20 mm circle of the frame.
Stopping down 2 stops helps but does not solve it."
I don't know why this is such a difficult concept to grasp, or why photographers try so hard to convince themselves that a 120 macro lens will perform on par with a 150 lens at infinity. It is no different for any other "true" macro lens made. They are specialty lenses designed to do a certain job. No lens, or at least any I am aware of, perform equally well across the board.
Case in point is Nikon's own micro lenses, which I've owned and used for over 30 years. The early models, such as the 105mm/f4 micro, is, in my opinion, the finest performing 105 micro they ever made in the macro range (1:10 and closer). However, its performance at longer distances and infinity was average at best, and no match at all for the famed 105mm/2.5 "standard telephoto" lens.
Years later, and a couple of "upgrades" later, Nikon introduced the totally redesigned AF 105mm/f2.8 micro lens, greatly improving its performance at infinity, but at the cost of diminishing some of its stellar macro performance. But this is what customers seem to want. They would rather have a "do all" lens that performs mediocre in all focusing ranges than a superb performer at either end.
If your objective is the best quality macro image, then there's no substitute for the 120 lens. If macro mode isn't your chief concern, then you'd be better off with the 150 or 180, and use the occasional extension tube or even close-up diopter.
There is no superb performing "do all" lens. As should always be the case, pick the right lens for the job. Different horses for different courses.
Michael H. Cothran