General Goodness:
* Bene- (Latin for "well" or "good"): *benevolence* (kindness), *benefactor* (someone who does good deeds)
* Bon- (French for "good"): *bonheur* (happiness), *bon vivant* (someone who enjoys the good things in life)
* Well-: *well-being* (state of being healthy and happy), *well-intentioned* (having good motives)
Specific Qualities:
* Kind-: *kindness* (the quality of being kind)
* Vir-: *virtue* (moral excellence)
* Just-: *justice* (fairness)
* Right-: *righteousness* (moral uprightness)
* Worth-: *worthiness* (deserving respect or praise)
* Excellent-: *excellence* (the quality of being outstanding)
Other Options:
* Goodness: This is the most straightforward way to make "good" an abstract noun.
* Good-: This can be used in some phrases, like "goodness gracious!"
The best prefix to use will depend on the specific meaning you want to convey.