The best replacement for 17-40 is 24-105.

The best alternatives to 17-40 are rated as following:
★★★★★  24-105
★★★★★  17-55
★★★★  16-35
★★★★  24-70
★★★  10-22
★★  16-35 ii
★★  15-85
★★  16-28
★★  18-55
★★  10-22mm
★  16-35 review
★  24-105 canon
★  17-50
★  16-35 canon
★  17-35
  tamron 17-50
  11-16
  15-85 canon
  12-24
  16-35 canon lens
  sigma 17-50
  tamron 17-35
  16-35mm
  canon 10-22
  sigma 12-24
  17-85
  canon 15-85

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Speaking about 17-40, one probably shouldn't forget about 5d.

Other search terms related to 17-40 and their ratings are:
★★★★★ 5d
7d
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Google Trends

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17-40
24-105
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