Neutral: This is the most common word for something not having a positive or negative connotation.
Indifferent: This implies a lack of interest or concern, suggesting that something is neither good nor bad because it's not important.
Ambiguous: This suggests that something is unclear or open to interpretation, making it difficult to classify as good or bad.
Objective: This implies a lack of personal bias, suggesting that something is neither good nor bad because it's simply a fact.
Apathetic: This suggests a lack of emotion or feeling, implying that something is neither good nor bad because it doesn't evoke any response.
Unremarkable: This implies that something is ordinary and unremarkable, neither particularly good nor bad.
Unbiased: This emphasizes the absence of prejudice or favoritism, suggesting that something is neither good nor bad because it's evaluated fairly.
Equivocal: This suggests that something is open to multiple interpretations, making it difficult to categorize as good or bad.
The best word to use will depend on the specific context and what you want to emphasize.