Roland nicely clarifies the details, and his discussion confirms my experience with Nikon's slower 28s (3.5, 2.8 ) in K/AI/AIS. I have used these quite a lot over the years. The 28 3.5s are good at f5.6-11 and inexpensive (less than 100 USD) though I find the 28 2.8s to be a little better. The consensus view holds that the 28 2.8 AIS is the better lens among these and, for resolution, arguably the best of Nikon's wide angles prior to the introduction of the AF 28 f1.4. The 28 2.8 AIS has exceptional close focusing performance as often noted; center frame resolution and contrast is quite good, and holds up well out toward the edge of the frame. The 28 2.8 AIS seems to flare easily, however, and at longer distances the 28 2.8 AI seems to equal the 2.8 AIS while also providing somewhat better edge resolution. These notes are general impressions and, it goes without saying, others may have different perspectives.
One of these days, I hope to acquire a modern lens or two. But until then, I can at least pretend that old Nikkors are OK...Robert