Why one ranking is not enough
A food can look impressive per 100 g yet deliver much less in a realistic serving, or it can look dense per serving while becoming less efficient once calories are considered. That is why a good comparator should let the user switch the ranking basis instead of pretending there is one universal answer.
Seeing those different rankings side by side helps users make better trade-offs for meal planning. A user trying to maximise vitamin C with minimal calories may want a different answer from someone trying to add calcium in a compact portion.