C'est "valorisant". If something makes you feel important and useful, it sort of give you more selfworth (value), hence the word "valorisant" (same family of word as value). Gratifiant is another good word, but not one I use much. Satisfaisant doesn't seem appropriate in my opinion, it sort of mean "just about enough to keep you going"

Rewarding = gratifiant; and fulfilling = satisfaisant. C'est gratifiant/satisfaisant d'être professeur des écoles.