The falacy in this argument is the small number of times you actually benefit from edge to edge sharpness. It rarely comes into play, and the further assumption that when it does the DA 18-135 isn't good enough. IN the pictures I've already posted, it makes no difference to the image.
Even in images like this
The edge sharpness is adequate... taken from the edge..
As long as your subject is located by rule of thirds or inside that frame, the 18-135 is excellent even at 135.
The appeal of the 77 is it's ability to create smooth OOF areas in shallow DoF images and excellent control of CA, maening very good micro-contrast. ANd any lens that goes to ƒ1.8 is going to be prized. And that's where most expensive lenses excel. But as an older lens, the purple fringing can be worse than expected in a more modern lens. I've certainly never seen anything like it using my SIgma 70 macro. but then, there is a heavy weight cost to carrying heavily corrected glass.
Quote: Meaning it is not up to 135mm that 18-135 is better but only after... when you want to crop 200mm.
Show me. I'll believe it when I see it. At web size can you even see a difference?
I frequently carry both the SIgma 70 macro and 18-135, I take the 18-135 off the camera for macro and some landscapes, but 90% of the time the 18-135 is the lens to use. And 90 % of the time the Sigma won't even do what the 18-135 will do. If you want to carry one lens, carry the one that does everything, even if it doesn't do some things terribly well. Don't be dreaming that you can use a lens like the 77 for 135 without a TC, and now were talking a couple grand instead of $400.