My advice is to not consider IQ at all when choosing between these lenses. Both are about as good as it gets.


Basically, you just have to choose between IS + macro capability and the extra stop (f/2) of the 135.


Keep in mind that the 135 only has an advantage for *moving* subjects indoors. For relatively still subjects, IS gives the macro a big edge. If I had to choose one for pics of kids in lowish light, I would choose the macro, but then... I don't try to capture action. For this (dancing people) the 135 of course has the advantage. Keep in mind though, that even with the extra stop, it is difficult to get good sharp pictures of action in low light (at least for me it is).


The MFD of the 135 might be a factor for baby pictures. If you like head shots or head and shoulder pictures, (this may sound like a joke, but it is not) the macro may be the better way to go for this reason. Another thing to consider that many people do not: when taking pictures of small people the dof is shallower and background blur more pronounced than when taking pictures of big people. For babies, I usually use f/4 or slower on full frame (which is about f/2.8 on a crop body). Stopping down negates the advantage of the 135.


In my mind, the macro has the edge for versitility becuase of the IS and macro capability. I would only get the 135 if I was primarily shooting action or if I was in love with the background blur it gives at f/2 (which I happen to be).