WordNet sense 1 (based on sound reasoning or evidence):

well-founded

WordNet sense 2 (exercising or showing good judgment):

sound

WordNet sense 3 (showing reason or sound judgment):

sensible

WordNet sense 4 (marked by sound judgment):

sane

WordNet sense 5 (consistent with or based on or using reason):

rational

WordNet sense 6 (not excessive or extreme):

fair, fairish

WordNet sense 7 (being within reasonable or average limits; not excessive or extreme):

moderate, moderate