These questions come up from time to time, so here is a copied response from another thread just to have it in the lens review section. Note I may update this from time to time so comments about other lenses are not necessarily in order of focal length:
I have shot most every lens available on the Mamiya/Phase body's and while I did not do extensive, scientific testing with each one, I will summarize my findings; I hope it helps guide your decisions:
28 AF D: Can we say sample variation. Some are very good once stopped down. My current one is very good at f11, but is definitely best at f16. Even on my P65+, at f16 the corners show some softness but are totally usable. If you're a perfectionist, consider it a lens you will crop to 30mm effective or so, and then shoot a little loose with it.
35 AF: They are variable, plain and simple. I had one that was excellent and it still showed some softness in the corners. However, I produced a nice image in Canyon De Chelley with it in front of my P45+, and even the corners looked fine on a 24" x 32" print. This lens has slightly lower contrast than the 28D or 45D. That said, a good copy should be fine on all cams except the P65+ where you'd probably want to crop off the last few mm of IC.
45 AF: I tested 4 versions of the pre D and they all sucked in the corners on my P45+. Center to 2/3rds out was excellent, but the corners were horrible and would have required a crop to about 50mm effective to be usable. I then tried one of the early D versions and same thing. Then about 6 months later, I got word of a few folks claiming their D version was great, so I tried one more time and got a good one myself. This one still shows a touch of corner softness on my P65+ but remains fully useable corner to corner for print purposes. The 45 is one of my most used focals for landscape.
55 AF: I've shot two different copies of this lens and both were quite good. Not as high of contrast as the newest D lenses but as sharp. They have the old style cheapie body and focus ring, but a very good performer for the money.
55 LS: Great lens, on par with the 80 and 110, and nice edge falloff when used wide open, very good corner to corner at f5.6, outstanding at f8 up.
80 AF: Older standard version had sample variation and the cheap body and AF ring, but very good performers in general -- like the 55 above. The D version is notably better with improved contrast and improved corner performance at the wider apertures.
80 LS: First impression was, "Oh yeah!" It has a more classic Schneider rendering -- very sharp and contrasty wide open in the center, with the extreme corners gently fading off in sharpness with a creamy bokeh. Stopping down one moves the sharpness out further, and stopping down two leaves it sharp and contrasty corner to corner. Stopping down 3 or 4 (f8 and 11) are the prime apertures for outstanding corner to corner sharpness and contrast.
110 LS: In a word, maybe even better than the 150 f2.8D I commented on below, yet has the classic Schneider rendering like the 80 LS. Gorgeous falloff wide open and laser crisp corner to corner by f4.5.
120 Macro. There are at least three and possibly 4 versions. The first one (or two) are all manual, meaning you have to manually stop down the aperture and focus, and with the latest Phase bodies, your metering pattern will default to spot with any all-manual lens mounted. The latter two are considered AF lenses, but both still are manual focus only and only allow camera-controlled aperture setting and automated metering. The most recent one is a "D" version and has some extra pins to allow for firmware modifications and more communication with the body. I have owned or used all 3 and honestly, the "D" version is a skosh better than the predecessors. Not that the predecessors are bad, they are in fact excellent, but the latest D version is a stunning performer.
150 f3.5 AF: Very good lens for the money, but needs to be stopped down one or two for best performance. Like the other pre-D designs, contrast is lower than the newer f 2.8 D version.
150 f2.8 AF D: In a word, this is perhaps the best lens I have ever shot or tested for any camera period. It is excellent corner to corner wide open with great contrast. Stopping down simply adds DOF and maybe a touch of contrast for the first few stops -- that's it and not much more to be said.
50mm Shift Manual: Another excellent lens. Sharp across the frame, even shifted on the P65+. I have tested C and N versions of this lens and frankly never seen a dog. Be sure to meter and focus BEFORE shifting.
200 f2.8 APO manual: This lens is amazing. In reality very nearly as good as the 150 f2.8 AF D. Only shortfall is minimum focus distance is a longish 2 meters. Upside, is Mamiya made a 2XN converter that works extremely well with it, leaving it very sharp and usable wide open at an effective 400mm f5.6. The converter does add a bit of barrel distortion that isn't visible without it, but still a super combination.
210 AF ED: Excellent lens, optical performance and contrast as good as any f4 APO out there, but a notch behind the 200 f2.8 APO at any aperture.
300 AF APO: Some sample variation, but most have excellent center sharpness even wide open. Some leave corners a bit soft at the wider apertures, but I had one that was awesome all the way across by f5.6. Great lens for the money.
55-110 AF Zoom: Again some significant variation in copies. I tried two of these and they were okay, but not so great they ever got mounted to the camera. Then I got one that was amazing and wish I hadn't sold it. Really good at the 55 end and just a tad less so at the 110 end. As with all older lenses, these get significantly better when stopped down to f8, 11 and 16, but the best will be fully usable wide open, even on a full frame back. As with most wide to tele zooms, this lens exhibits pincushion distortion at the short end and some mild barrel at the long end. The sharpest ones showed very slight CA along high-contrast edges, but this is easy to fix in C1.
105-210 AF Zoom: Ditto what I said for the 55-100. The two I shot tended to be better at the longer end and weaker at the short end, but again, from f8 and up, very good all around. In fact, this zoom at 210 is essentially as good as the 210 AF Prime. Major difference is distortion -- this lens exhibits mild to moderate barrel distortion across the range.
75-150 AF D Zoom: Again, earlier samples weren't as good as the later versions, and by all accounts most folks find this a very, very good lens. It is by far my most used lens and is on my camera probably 70% of the time. Very good at f5.6, excellent centrally at f8 with VG corners, and excellent corner to corner at 11 and even 16.