We did some testing with different 3D printers and my conclusion leads to:
1.75mm is actually 1.75 ±0.05mm is the optimal size for 3d printing, with 1.70 being a realistic goal to reach
3.0mm is actually 2.85mm ±0.05mm is the optimal size and I refer to Bootfeeders answer.

The mystery is solved and we now know how to proceed.
We will soon launch our own enhanced ABS and PLA filament branded as "3Dfilamenta", but still got some more testing to do before going live. Hopefully our product will remove most problems with current ABS and PLA or at least minimize the problem we have today.