Looking over my notes, it is obvious that my NPK 105/2.5 P non-AI is my most used (and favorite) lens. Thus, I would like to add another 105/2.5, either non-AI or AI. I use a hand-held meter about 95% (or more) of the time, and so the AI capability is not a priority. Performance characteristics are my priority, and to some degree build quality is a factor. After the research I have done, I am favoring the 105/2.5 AI PC version (knurled focusing ring). I welcome any comments.