Great Always plan for EOS 600D

I have long been looking for a (scorned) immerdrauf lens and demand in some forums. Unfortunately, there were many answers and after more questions ...
After many doubts, I have tested in a very nice photo shop 3 lenses on my EOS 600D:

1) 15-85 (750)
2) 18-135 STM (400)
3) 24-105 L (900)

I was surprised by the results: test images with both good and poor light each in the range 18mm (24) and 85mm as compared showed a surprising result: the expensive 24-105L had in the range from 85mm distinct color distortion - I had not expected. The 15-85 showed very identical images to the much cheaper 18-135. Since the choice was simple ...

That may also answer only Canon ...

I spent 2 vacations now with 18-135 STM and made a lot of pictures - and am satisfied. Brighter are the other two lenses on the 600D, anyway. The quality of the lens is also okay (especially for the price) and it really is super fast and quiet.

Important: it is the 18-135 STM (there is probably an older without STM!)
Who really expected more image quality, L lenses should take far beyond the 1000 in the election!