I do not have any personal experience with either of these lenses, but in terms of construction, durability, and quality, they seem to be quite similar. They say they are some of the best Tamron lenses.
For portraiture, I’d go with the 28-75mm. 17mm is just too wide for faces, and when I use my Canon 17-55mm f/2.8 lens for portraiture, I find myself shooting at 17mm far more than I intend because I find myself zooming out instead of stepping back.