General:
* Heartfelt
* Sincere
* Genuine
* Authentic
* Earnest
* Profuse
* Deep
* Intense
* Passionate
* Ardent
More specific:
* Tender (for feelings of love, affection, or care)
* Grieving (for feelings of sadness or sorrow)
* Anguished (for feelings of extreme distress or pain)
* Enthusiastic (for feelings of excitement or strong interest)
* Fervent (for feelings of strong religious devotion)
The best word to use depends on the specific context and the specific emotion being conveyed.