50mm F1.8 is best general use lens (even center-to-corner performance all apertures, least distance sensitive of fast lenses, cheapest - an excellent performer).
1.4 has better contrast at F2, but worse corners at 2, 2.8,4, not great at 1.4.
1.2 has more sensitivity to distance, performs very well at wide apertures
at 5-15 feet (except corners), is lousy near infinity at wide apertures.
55 F2.8 is excellent all apertures, all distances, vignettes slightly at 2.8,
a sharp lens, but not a good speed lens.

All perform very well by F5.6, hard to tell apart, except maybe corners of some F1.2's near infinity, or at minimum focus.