[ricardobeat]

You got it backwards on “I adapt to whatever shape font has” though.

The Mac rendering while a little less sharp means letters always have roughly the same shape, as intended by the typeface authors, while the Windows anti-aliasing distorts them unpredictably depending on where and which pixels they fall onto. Two ‘a’s might look slightly different within the same word because they fall into different alignments on the pixel grid. This is what gives it the wonky appearance.