My .02...
I think the 28D is "good enough" in the corners for serious use on full frame backs, but it is very wide at about an equivalent of 19mm so may be overkill unless you need really wide. On a crop back, IMO it moves into the "must have" category as THE wide at about a 23.
I have a very good copy of the 35 AF (about a 25 on FF), but to clarify it is not in the same league as say the 55 prime. Also both the 28D and 45D are sharper and show better contrast centrally, but my 35 is better in the very corners than either on FF, and since I don't shoot that wide very often, this 35 remains my wide of choice.
The 45D, at least every one I've tried, has useless corners on a full frame back. However, this is the very corner and should not even show up on crop backs, so it becomes a very useful focal there. The ones I tested were as sharp in the center as the 55, so excellent, but if you needed to crop out the corners for a full frame back you'd be back to almost the 55 FoV. We need a new design (clutched) 55 AND a re-design on the 45 that keeps it sharp to the corners on FF.
The 75-150 and 150/2.8 debate... The 150D is such a phenomenal lens it is very tough to part with once you've shot with it. The 150/3.5 doesn't ever really match it, being less sharp and showing lower contrast at the wider apertures, though gets pretty close at f8 and f11. By comparison the 2.8 lens is as sharp AND contrasty wide open as it is at f8, just with less DoF, and shows a bit of falloff wide open at 2.8 that can be used creatively. I know that is a strong statement, but ask anybody else that owns one and they'll tell you the same thing. It is the best lens I have ever owned for MF period, and FWIW, my 80D is not far behind it.
The D zoom is very good too. It needs to be stopped down to f5.6 and is sharpest at f8 and 11, and does give up contrast in the upper half of the zoom range, especially when compared to the 150/2.8 even stopped down. That said, it is the lens that is mounted to the camera most of the time as it is just so versatile.
A FWIW on the older zooms, the 55-110 and 105-210 AF. These can be very good too, though you need to sort through a few copies to find good ones. (For example, my 55-110 is good enough at 55 that I recently sold my excellent copy of the 55 prime.) Right now I have both of these older AF zooms, and IMO they compare favorably to the D zoom at f8 and up. Note that I use these two zooms mostly for landscape where I am almost always stopped down to f11 or 16 depending on lens and focal. As such the wide open performance from these zooms is not critical for my uses, and I would rank them less desirable at the wide apertures. Also note my particular copy of the 105-210 is stellar at the longer end, so really makes a nice 210 with added versatility at around the same price as the 210 prime.
A note on Macro. The Mamiya 120 macro is silly sharp and has outstanding contrast, nuff said. However it does show rather significant falloff wide open at f4 and has a kind of clumpy rear bokeh wide open. As such, I see it as more an f8 and up lens, and it is manual focus. Another option for less critical macro is adding a #1 or #2 tube to the 150 or the zooms. While they won't get as close and performance is not in the same league as the dedicated macro, the combos are surprisingly sharp. Like the macro, the tubes disable AF so your lenses become manual focus. The tubes are also smaller and lighter than adding a 120 lens, but if you have to buy them new, the #1 and #2 pair can cost about the same as a used non-D version 120! Finally, Mamiya offers an AFD bellows complete with a lens coupling cable and a 58mm reversing ring for the old 80/55/45 that gets you larger than 1:1 with excellent quality. These can be found new on eBay for under $1000. Optional reversing rings are available for 67mm and 77mm filter size lenses. The AF bellows does NOT have tilt, swing rise and shift movements like the older manual bellows had.