My accumulated notes on 85-105 LTM lenses say the following. Admittedly, these remarks aren't from my own experience, so feel free to disagree. For instance, images from the 85 Serenar given further up this thread show these are no slouch at all.
85 /1.5 (Leica, Canon, Nikon) - expensive, outperformed by slower models.
85 /1.8 Canon (black) - Undoubtedly best of the Canon 85s, and one of the best (and possibly the very best) of any LTM 85...
85 /1.9 Serenar (chrome) - not as good as other Canons. [But not bad t'all]
85 /2 Serenar (chrome) - not as good..
85 /2 Nikkor (black or chrome) - both superb, but black is lighter.
100 /2 Canon - very fine, but heavy
100 /3.5 Canon - tiny, sharp, coveted. A long-focus, not tele design.
100 /4 Canon - predecessor to 3.5, and not as good.
105/2.5 Nikkor - one of the best LTM lenses ever.