It all comes down to personal experience, and then the particular lens and finish point of the project. I own a canon 7-56, optex converted to 8-64, and I'm extremely pleased with the sharpness, lack of breathing, and overall performance of the lens.
I've shot with the 7-63 factory super 16, along with 11-165, 8-64, and angeniex 7-81, and countless other super 16 lenses, and while ive never done a side by side test of the same material, I find my personal lens to compare very well footage wise on Digibeta and film print alike.
Like all products, luck and maintenance are all important.
