Nearly everyone needs/wants a general purpose zoom lens - also referred to as a standard/normal zoom lens or a walk-around lens.
Typically: This is the lens that you leave on your camera for everyday needs. This is the lens you photograph your family with. This is the lens you capture life with. This is the lens you travel with. This is the lens responsible for preservation of your memories. This is the most important lens in your kit.
Because this lens will probably be your most-used, because this lens will capture what is most important to you and because the quality of the lens makes a huge difference in your photographs, I highly recommend buying the highest quality standard zoom lens you can afford.
I consider the heart of the general purpose focal length range to be about 28-70mm for a full frame camera or 18-45mm for an APS-C format DSLR camera with its 1.6x FOVCF. Since these two focal length ranges are quite different, and because some lenses are not compatible with full frame format DSLR cameras, I'm going to separate my recommendations below. Read on for the APS-C recommendations or go directly to the Canon full frame general purpose lens recommendations.
1. Canon EF-S 17-55mm f/2.8 IS USM Lens
Best-Available Image Quality, Wide f/2.8 Aperture, Great Autofocus Speed & Accuracy, Image Stabilization
If I were forced to pick only one APS-C lens, this would be the one. The EF-S 17-55 gives you the best Canon zoom lens image quality available along with a wide, constant-over-the-zoom-range, max f/2.8 aperture (vs. a variable max aperture) that is useful for stopping action in low light or for creating background blur. Also included in this lens are fast and accurate Ring USM-driven autofocus and valuable image stabilization.
2. Canon EF-S 18-135mm f/3.5-5.6 IS STM Lens
Wide Focal Length Range, Great Value, Small, Light, Image Stabilization, Great for Movie Servo AF
The EF-S 18-135 STM is packs a long range of focal lengths into a small, light, image stabilized body. It provides decent image quality and performs especially well when recording video using Movie Servo AF. When purchase in a kit with a DSRL camera, this lens has a great value price tag.
3. Canon EF 24-105mm f/4L IS II USM Lens
Excellent Image Quality, Excellent Build Quality, Great Focal Length Range, Great Autofocus Speed & Accuracy, Image Stabilization, Weather Sealing
The 24-105's focal length range slides toward the long end of the general purpose range for APS-C body users, but it is still very well-loved by this group. The fixed f/4 max aperture falls in the middle between the f/2.8 options and the variable max aperture lenses. If you are not stopping action indoors without flash, f/4 works great for most purposes.
4. Canon EF 24-70mm f/2.8L II USM Lens
Ultimate Image Quality, Excellent Build Quality, Wide f/2.8 Aperture, Great Autofocus Speed & Accuracy, Weather Sealing
As with the 24-105 L, the 24-70L II's focal length range slides toward the longer end of what most want in their APS-C normal zoom lens. The 24-70L II is all about performance and this lens represents as-good-as-it-gets for standard zoom lens image quality - very impressive. The 24-70L II lacks image stabilization and carries a weighty price tag. This L-Series lens is full frame compatible.
5. Canon EF 24-70mm f/4L IS USM Lens
Excellent Image Quality, Macro Capabilities, Excellent Build Quality, Good Focal Length Range, Great Autofocus Speed & Accuracy, Image Stabilization, Weather Sealing
As I write this summary, I would not consider the 24-70 f/4L IS a great value as the 24-105L IS is readily available for a significantly lower price. But, this is still a very good general purpose lens choice - especially with the impressive macro capabilities this lens has. Again, the 24-70mm focal length range is somewhat long for many APS-C camera owners. And again, this is a full frame compatible, weather-sealed L-Series lens.
