I'm an artist, and a professor of art & design. A lot of my work focuses on landscape. All my cameras are APS-C, all the lenses are Canon. I want a 6D pretty bad.
I've gotten hooked on canonrumors forums within the past year, and learned quite a bit here. This thread a consistently fun and informative one! It's interesting to me that even the cheapest Canon lenses are often very capable.
15-85mm is my current favorite, because the range of focal lengths are exactly the ones I use most. IQ is really sharp, with vivid colors and contrast. Landscapes love this lens, and I don't have to carry anything else on day hikes.
18-135mm is an extremely useful range, and it's light, so I take it on backpacking trips.
85mm f/1.8 has given me some really dreamy candid portraits.
70-200mm f/4 excels when details are the key thing, it makes nice big colorful prints without much PP.
24-70mm f/2.8 and I don't really understand each other yet, but we're working at it.
60mm f/2.8 is actually pretty versatile, useful for macro (insects, plant surfaces, textures) and also portraits. Macro video of really tiny stuff turns out awesome.
10-22mm is an awe-inspiring device, the ultra-wide offers a very new and different way to see. Also very light, good to carry around all day.
50mm f/1.8 makes the sharpest pictures of any of my lenses, including the L's, with a sweet spot at f/10. The normal perspective limited to a cropped field of view on APS-C bodies is sometimes frustrating, and the focus ring suuuuuuucks. A love/hate situation, with far more love than hate.
400mm f/5.6 is very sharp, with rich saturated colors, difficult to hand hold but rewarding when it hits.
55-250mm was one of my first three lenses, and I still use it (kind of a lot) for the combination of image stabilization, portability, and a pretty long reach.
18-55mm was my main landscape lens for a few years, but rarely gets used anymore.