Best affordable AI model for communication that remembers context?

I’m building a communication‑focused AI system and I’m looking for recommendations on the best model that can:

• handle long conversations and remember previous context
• give strong logical and structured responses
• support multiple languages
• and isn’t too expensive to run at scale

If you’ve tested different models for real‑world communication tasks, which one gave you the best balance of quality and cost?

Looking for something reliable for customer support, email replies, and chat automation.