Synonyms for "Good"
General Positives:
* Excellent
* Wonderful
* Fantastic
* Amazing
* Brilliant
* Great
* Terrific
* Super
* Fine
* Nice
* Pleasant
* Delightful
* Satisfactory
* Acceptable
* Worthy
* Suitable
* Beneficial
* Advantageous
* Positive
Specific to Quality:
* High-quality
* Superior
* First-rate
* Top-notch
* Premium
* Exquisite
* Elegant
* Refined
* Impeccable
* Flawless
Specific to Morals:
* Virtuous
* Moral
* Righteous
* Ethical
* Honorable
* Just
* Decorous
* Upright
* Decent
* Kind
* Compassionate
Specific to Feelings:
* Happy
* Joyful
* Cheerful
* Glad
* Content
* Pleased
* Satisfied
* Lucky
* Fortunate
More Informal:
* Cool
* Awesome
* Rad
* Sweet
* Nifty
* Legit
Opposites:
* Bad
* Evil
* Wicked
* Poor
* Inferior
* Unworthy
The best synonym for "good" will depend on the context and what you want to emphasize.