EFS 17-55 vs 15-85 in low light

Nice pics.  Of all the pics there's only one I would consider "low" light, the Cuba pic of people playing a game at a table.

Hence if these are a accurate representation the type of pics you take the most then the 15-85mm IMHO would be a better "general purpose" travel zoom -- that's I bought one.

Since you seem to take quite a few landscape shots, you would probably like the additional 15mm wider angle of view.  Need to remember at the wide angle focal lengths, there's a larger change in the AOV (angle of view) for each mm focal length than at the longer focal lengths.

15mm AOV = 84°

17mm AOV = 78.3°

FYI, you can see a review of the 15-85 IS: here

It has a photos taken at the different focal lenghts (15-85mm) to give a idea in the difference between 15mm & 18mm, and 55mm & 85mm focal lengths.

Cheers & Good Luck with your choice,

Jon