"Which word is better?"
If you miss someone you love, then you could say, "I miss my love," where "your love" is your wife or girlfriend.
If you miss them so much because, for example, they are gone forever, you could say, " I am heart broken," or "She broke my heart."
But, if you are being poetic, I suppose you could say something like, "That day, I left my heart on the floor. I will never love again." (I have never heard that before, but if you are being poetic, I think it could work). Or "I left my heart" somewhere, like in the song, "I left my heart in San Fransisco"