Informal:
* Ça me va (literally "That suits me")
* Ça marche (literally "That works")
* Pas de problème (literally "No problem")
* C'est bon (literally "It's good")
* D'accord (literally "Agreed")
Formal:
* Cela me convient (literally "That suits me")
* Parfait (literally "Perfect")
* Très bien (literally "Very good")
The best choice will depend on the specific situation and your relationship with the person you are speaking to.