The designers for Finale and Sibelius were not thinking very well when creating their music engraving fonts. The first four font examples belong to these programs respectively. You will notice that their objects have a lot of thin lines; even when blown up to a larger size. Finale’s and Sibelius’ engraving fonts look elegant enough when they’re that large, but this is not the size at which these objects are employed. They are ultimately put to use at a much smaller scale. So, their thin lines get scaled down and lose much of their presence on the page. The thin lines become even thinner and it becomes hard to spot the accidentals and rests amidst the music.
When designing an engraving font one must keep in mind that when the objects are eventually scaled down to size the line thickness will also go down. So line thickness needs to be proportionally compensated for at a larger “zoom in” size. The Feta font almost looks unnaturally bold at a larger size. That is because it is not used at this size, it is meant to be employed much smaller. The Feta font created by the LilyPond team has its “actual size” in mind all the time. This is one reason I think LilyPond’s engraving fonts are superior to any other.