I often wonder (don't regret really, just ponder) what it would be like to have just the best custom kit for each job*. A specialised landscape, sport and street/travel kit.
One lens/camera combo that I would have kept for that thinking, if that was how I chose to go would have been the Canon 1Ds mk2 and the 400 f5.6L. The lens, like my other favourites from Canon, the 70-200 F4L and 135L, was not stabilised, but it hand held well, easily lower than it's reciprocal focal length/shutter speed equation.
1Ds mk2 with 400 f5.6L with 1.4 teleconverter wide open at 1/125th, cropped to 1400x1700 from the image below.
The OMD sensor has similar properties and the same pixel count, but the quality out of those old Canons was way better than anything I had seen before and the colour more natural than the lush colour of the current crop (much like the Olympus look). I remember showing a friend, a 5d mk2 user, an 8x10 of the above and telling him the long list of compromises made to get it. I don't think he believed me until I showed him the "full monkey".
The full file.
Ahwww, cute. 5d Mk2 and the same lens.
The lens was a giver. I remember trying to convince a customer to buy it over the 100-400L, but he went with the versatility. He later regretted the decision after we compared identical images from similar cameras. To top it off, after selling it and the 135L to a shop in a neighbouring city, I found out from my wife, that a friend from her work bought them both and has them back here. Haunted still.
The Olympus glass is the equal of the Canon I had (the 45 is nearly identical to the 85 f1.8 in look and performance, but less than half the size, the 75 matches or beats the 135L, 40-150 is better/faster/longer than the 70-200 f4L and the 75-300 surprisingly close in end result to and easier to use than the 400 and a little longer), but if I had held onto those lenses they would have been (were) the nucleus of a good SLR sports kit.
*Fuji for landscape (14, 18-55, 60 and 90 macro), Olympus for street and portrait (17, 25, 45, 75) and Canon for sport (24, 40, 135, 400). Selling and buying gear for me has been a bit of a merry-go-round and I don't regret most transactions, but some clear thinking in hind sight would have spared me from selling off a couple of camera and lens combo's that just worked.
The ideal is one kit that works (that I have), but it is sometimes fun to remember past successes, just not dwell too much on the ones that got away.