I think the MathML sizing, positioning, and spacing of glyphs is strictly worse in every example at your link, sometimes quite dramatically. In a few cases (like the deeply nested fraction) the LaTeX is also not great.
This would be a fairer comparison if they saved the LaTeX as SVG outlines, or as a higher resolution bitmap. As it is the LaTeX version looks fuzzy on my high DPI display.
I dunno. Looking at the math rendering torture test at https://mdn.mozillademos.org/en-US/docs/Mozilla/MathML_Proje...
I prefer the MathML version in 15 of the examples and the LaTex in 11. (No preference in the others.)