Formal:
* Je vous ai manqué. (This is more formal and can be used with someone you respect or don't know very well.)
Informal:
* Tu m'as manqué. (This is more informal and is used with friends, family, and loved ones.)
More poetic/emotional:
* J'ai senti ton absence. (This literally translates to "I felt your absence" and expresses a more profound sense of missing someone.)
* J'ai eu envie de toi. (This translates to "I have craved you" and implies a strong longing for someone.)
The choice of translation will depend on the specific context and your relationship with the person you are talking to.