The use of "ce" as subject is different from the use of "ce" as descriptive pronoun. "Ce" as subject will never be plural, but the descriptive pronoun has to match the noun. So, for instance, here you have "Ce sont les meilleurs", but you would have to write "Ces filles sont les meilleures" ("Those girls are the best")
As someone said to me in another thread (and I noted down, sorry for not retaining the attribution, though @sitesurf is usually a good suspect):
> "Ces" is a demonstrative adjective. It needs to be attached to a noun > (i.e. it doesn't act as a pronoun.)
[This isn't really different from what @PtitSeb has said, just put differently.]
Comme bon et bien, meilleur et mieux peut être déroutant pour les étudiants français. Meilleur est la forme comparative et superlative de l'adjectif bon (bon), tandis que mieux est la forme comparative et superlative de l'adverbe bien (bien). Lors de la traduction en anglais, il n'y a pas de différence entre meilleur et mieux, d'où la confusion.
Yes, ce is a pronoun, which stands for a noun. It's an "indefinite demonstrative pronoun", which is why it remains 'ce' (not ces). When you first read the pronoun, you don't know if it's plural or not (though you later find out), which might make it easier to remember why it's invariant.
Okay, Jean. I think the issue is that you have a set phrase in mind in English and you want to translate that to French in a literal, word-for-word fashion. What I am suggesting to you is that "best" (pl) in French is "les meilleurs" or "les meilleures". If you leave out the article in French (ce sont meilleurs), it would be "these are better". If you want to say "these are best" (i.e., "the best ones"), you have to think in French: "ce sont les meilleur(e)s"