It's interesting to see the differences in what people choose. I've been thinking about this because how and where I take photographs has changed. I used to grab a camera and a lens and go for walks, limiting me to what I can comfortably carry in a small bag, but with the opportunity to come back the next day if I had the wrong lens for something interesting. Now I'm much more likely to go somewhere that I can't easily return to, and need a few lenses that can take care of anything I'm likely to want. I also have to balance what I want personally with what I need to do the work that I want to have -- architecture, product (especially jewellery), and theatre/event photography.
As I'm using a 4/3 camera, my focal lengths need to be doubled to convert to 35mm-equivalents. I also have two stops more depth of field than a 35mm camera, or one stop more than a 1.5/1.6x crop, so I need smaller apertures to throw backgrounds out of focus.
If I could only have one lens, like Irma, I'd take a good standard zoom. In my case that's the
14-54 f2.8-3.5, which is the lens that I used for the first year with my SLR. It's a good lens and covers just about all of my everyday needs. The quality is very good, and it's small and sealed. The only problem is that I don't particularly enjoy using it, and carry others instead whenever possible. Projecting into the future, I might take the 12-60 instead, but it's not on the market yet.
For two lenses, I'd take the
11-22 f2.8-3.5 for a wide-normal zoom. It's not quite as wide as I'd like, but the wider 7-14 f4 isn't worth giving up the length. I'd also keep my
35-100 f2 long zoom. I wasn't initially a big fan of this lens simply because it's so large and heavy. Without the tripod collar, it weighs as much as my heaviest camera with its battery grip and the 11-22 lens attached. With the hood in place, it's over 13" long, and even without the hood it's bigger than my Sony F828. This isn't something to pull out over Thanksgiving with the camera-shy nieces. Still, the quality, speed, and versatile focal length has finally won me over.
If I could have a third lens, I keep the 11-22 and 35-100 and add the
50 f2 Macro. It's a nice small lens with no real flaws, except for the focusing quirks that are common to macro lenses. It's excellent for product photography, and does pretty well for camera-shy nieces, too. While the 35-100 doesn't have nearly the reach non-photographers expect it to, the 50f2 is deceptively long and is really good for portraits and less intrusive photography.
I'd probably miss the ultra-telephoto of my 50-200 and the flexibility of the 1.4 teleconverter the most. That could always be fixed by adding a fourth lens like the 90-250 f2.8, but that's another thread.