Which is the correct comparative form in the sentence: He is a better singer than ___?

The correct choice in this context is that "anyone else" fits best after "than" in the sentence because it correctly conveys the comparative structure intended. The phrase establishes a comparison between the subject, "He," and other individuals. By using "anyone else," it implies that among all individuals considered, this person stands out as a superior singer, which aligns perfectly with the comparative nature of the sentence.

Using "anyone" alone does not adequately highlight the comparative aspect, as it does not specify that a comparison is being made with all relevant individuals. "Everyone else" is somewhat redundant and can be seen as unnecessarily broad when comparing with a singular subject, while "somebody" lacks the necessary comparative context and specificity to qualify as accurately as "anyone else." Thus, "anyone else" not only maintains grammatical coherence but also enhances clarity in conveying that comparison effectively.