>>3555217Nikon, Canon, Sigma, Tamron all have their problems.
The thing is it's more difficult to make a flawless large piece of glass than a flawless small piece of glass.
That's why it's unfair to compare the olympus lenses to the FF ones in that regard.
But if you are looking for perfect FF lenses, the Voigtlander guys did a magnificent job in their APO-Lanthar series.