After a series of comparative images, I see only a slight difference, in my opinion has the 16-105 better sharpness and 18-135 minimally better contrast. Colors are identical.
One can well evaluate the lenses so as equal. You but both can not get into the quality of the 2.8 16-50 or 70-300G. But are still very good lenses.
The 18-135 distorted visible at 18mm, much more than the 16-105 at 16mm! That speaks a little more for the 16-105. When A77 is indeed correct.
For the 18-135 over 100 grams lighter and about 100 cheaper.
The AF is at 16-105 louder but almost as fast (or slow when you think about the speed of 16-50mm). The Lock button I would have liked at 16-105.
So if you want to see more in the pictures, like architecture and landscapes photographed should take the 16-105, whoever wants to be happy to get closer, for the 18-135 is slightly better suited.
I need always like more wide angle, so I keep the 16-105 and 18-135 giving the back.