The Best Lens
I hear "all the time" people saying my favourite lens is ... and then they explain, it's the sharpest, it's the cheapest, it's the lightest...
No it's not, these are just the rationalizations. The real reason is that this lens is the one match their vision. Some people are "wide angle" people, some people are "tele" people...
My favourite lens is the Canon 70-200 f/4 IS. Actually that's one of the main reason that I switched from Pentax, with its vastly superior ergonomics, to Canon. It's half of the weight of the 70-200 f/2.8 IS and even that is starting to get too heavy for me, especially when I have to hold the camera/lens combo with just one hand because I have the flash in my left hand.
It's a great lens, fantastic optics, great IS but the most important is that the lens matches my vision, especially on an APS-C camera. I'm a tele guy. I like to simplify, I like to get in without shoving my camera into the face which often can be very dangerous. Often this lens allowed me to capture just the right magic without intruding and killing the moment.
I do have some wide angle lenses and uses them regularly indoors or for panoramas, but they are not my favourite.
This is a 110° angle photograph. The curvature is not from the wide angle but from the shape of the building. The Cathedral is built in the shape of an igloo and the common name is the “igloo church”. This was photographed with a 28mm on a Canon 7D which makes it the equivalent of a 44mm. This photograph is a composite of 12 raw images.
BTW, I just bought a Canon 40mm f/2.8, the pancake lens. I start to like it a lot. It's very small, it doesn't initmidate people and it's excellent indoor for the flash. I can easily carry the camera/lens in my right hand and the flash with an extension cord in the other hand.