I have 35, 85 and 135mm and additionally 50mm Zuikos.
I paid around 70 euros for 35mm(f/2.8), 40 euros for 135(f/2.8) and 250 euros for 85mm(f/2.0). The 50mm(f/1.4) came with together with OM-1n after I won the bid for 40 euros.
100mm(f/2.8) is cheaper than 85mm(f/2.0), difference in terms of Field-of-view is just 3 degrees. So, you won't go wrong with any one of the choice.
35mm(f/2.8): Fine from f/5.6->This is my landscape/Street/Group photos, so I did not worry about the performance at wide-open.
85mm(f/2.0): Finest lens, you will never regret.
135mm(f/2.8): Amazing lens but takes filters with dia 55mm, but 135(f/3.5) have dia 49mm.
50mm(f/1.4): I seldom use it, since I do not like this focal length.
Regarding cameras, I wanted to have mechanical only but in the mean-time I was curious about spot-metering capabilities so I went with OM-2sp.
Sooner or later, I will sell OM-2sp and get one or two OM-1ns.
Do not worry about metering accuracy or battery issue, if cash permits you can get yourself very nice external meter with spot-metering capabilities.