In 5e, alignment is already mostly defunct - it has almost no mechanical effect, and more of the effects is does have are legacy (like items keyed to certain alignments). I generally just use a loose 'good, or evil' idea and the occasional 'only someone good/evil can use this item,' with law and chaos giving an idea of how much you hold to tradition and respect for authority. The vague terms work pretty well; most people's idea of 'good' and 'evil' line up well enough with mine that it's not a big deal. I do this even when running Adventurer's League games that technically use the full alignment rules, because alignment is so mechanically distant that there's no good reason to delve into it beyond the 'no evil characters' rule. The only reason I don't ditch it for my own games is that some people like it, and people who don't like it don't actually have to interact with it.
I also don't think mechanical alignment really holds up well without major supernatural beings backing it, especially the 'law/chaos' axis who's definition is extremely shifty. If you have Elric's world with actual forces of Law and Chaos, you're literally aligned with a Power, and that works fine. But if you're just using alignment in general, I'm not sure what a LG PC in the equivalent of Rome who runs into the equivalent of Spartacus is actually supposed to do to be consistent with both letters in his alignment. If you make alignment a major mechanical part of the game you have to address this and similar arguments (plenty of which have come up in the thread), but if it's just a loose description that mostly doesn't do anything mechanically you avoid that.