Which Geologic time scale is the most accurate?
According to these Wikipedia pages - https://en.wikipedia.org/wiki/Geologic_time_scale#Table_of_geologic_time, https://en.wikipedia.org/wiki/Precambrian - the Precambrian is a "supereon" not an "eon".

The ICS International Chronostratigraphic Chart, ambiguously, puts "Eonothem/Eon" over both the "Precambrian" column and the "Hadean - Archean - Proterozoic" column, with the next column over being "Erathem/Era", which corresponds to what's in the other periods.

It seems clear that 1) the Hadean, Archean and Proterozoic are considered "Eons" like the Phanerozoic is (with their sub-divisions all being called "Eras"), 2) the Precambrian is a larger period of time that encompasses the Hadea, Archean and Proterozoic, and 3) there might be some disagreement as to how to name the period of time the Precambrian is; Wikipedia says "Supereon", which makes sense, but the ICS chart doesn't include that word and seems happy to have it share the name "Eon" with its immediate subdivisions. But the name is just a name, the more important things are how the different periods relate to each other, which is covered by 1) and 2).