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The 105mm f/1.8 AI-s is a favourite of mine, I find the way it balances on the larger FX bodies great, and I have no complaints about sharpness wide open, though I also don't print large. Here are a sample of portraits with the 1.8, all wide open except for the last one, at f/2.8.
Margot by philipjohnson, on Flickr
Rocio by philipjohnson, on Flickr
Alley Sue by philipjohnson, on Flickr
Smoking by philipjohnson, on Flickr
You will find that there are chromatic aberrations with this lens, LoCA being present with sunny, backlit situations. I used to own the 105mm f/2.5 AI-s and found it to be an excellent performer too, and if you would prefer the lower cost and smaller size I wouldn't hestitate to recommend it either. At f/2.5 it is already a great performer, with less issue with chromatic abberations. You really can't go wrong with either 105mm lens, and if you are content with the slower aperture the f/2.5 would likely fit all your needs.
For the 135mms, John H, Curtis, and a few others have a lot of experience, so hopefully they will chime in.