Oh, wow! I didn't think I would have kicked off such a storm here!
Haha!
Being the analytical type, I started a spreadsheet that lists my lenses and I began marking each lens as "Keep" or "Sell". There were two "Unsure" tags that I need to clear up for myself. The process was harder than I thought it was but it was a good experiment. I haven't used every single lens in recent times so I went by past memories and impressions. The FA 28-105mm f/3.2 gets some love because I remember how well it served me before I received a DA 18-135mm for Christmas. I have been using my FA 50mm f/1.4 so it's fresh in my mind but my FA 50mm f/1.7 draws a blank. Lenses I received as gifts from friends and family are untouchable. My collection of kit film era zoom lenses are nice to look at on a shelf but they aren't anything I think about at all.
Out of 45 lenses listed I think I marked 19 to sell. The list is missing three lenses : a M series 50mm f/2.0, a Lentar 135mm f/2.8 and Lentar 200mm f/3.5. All three would be marked as "Sell". I think with some more thought and evaluation I can make further cuts.
I am sharing a PDF of the spreadsheet. It was created in Open Office and then printed to a PDF. Hopefully it can be opened on other computers.
Comments are welcome, as always.