If "meanest" is referring to unkindness or cruelty:
* Kindest
* Most generous
* Most compassionate
* Most caring
* Most loving
If "meanest" is referring to being the lowest or smallest:
* Greatest
* Largest
* Highest
* Biggest
If "meanest" is referring to a mathematical average:
* Highest
* Largest
* Maximum
If "meanest" is used in a colloquial sense to mean "most unpleasant" or "most difficult":
* Nicest
* Easiest
* Most pleasant
* Most comfortable
To give you the most accurate opposite, please provide more context about how "meanest" is being used.