General Synonyms:
* Eloquent
* Articulate
* Vivid
* Poignant
* Emotional
* Powerful
* Moving
* Evocative
* Dramatic
* Meaningful
* Significant
Synonyms for specific uses:
* For art: Vibrant, evocative, dynamic, impactful
* For language: Fluent, eloquent, articulate, poetic
* For emotions: Passionate, heartfelt, sincere, intense
The best synonym for "expressive" will depend on the specific context of your sentence.