I love Nikon pre-AI lenses. These are the ones i have:
28/3.5: This is a strange lens with a unique look due to its strong vignetting and the way it produces nice sunstars.
35/3.5 PC-nikkor: This is a rare lens and I like it very much because it's more compact than the 35/2.8 PC-nikkor I also own. Optically is an "enlarged" version of the 28/3.5 pre-AI
50/2.0 "H": Everyone knows this is perhaps the best all-around 50mm lens by Nikon.
50/1.4 "K": Have not used it often enough, because i have the...
5.8cm f1.4 Nikkor-S: The bokeh king, i wish i had twelve copies of this.
135/3.5 Nikkor-Q: A lens with very pleasing bokeh and nice build quality
In the past i've owned also the 200/4.0 Nikkor-Q lens, first version. It was not the sharpest lens but it had extremely nice bokeh, and i sort of miss it.
All in all i'm more a Canon FD/FL lens fan, but those pre-AI Nikkors are lovely.