Based on your query, I recommend using ElevenLabs and ChatGPT in combination to create engaging speaking activities for your online one-to-one ESL classes.

ElevenLabs can be used to create synthetic voices in different accents, which can be used to expose your students to a variety of English accents. This can help them understand and adapt to different English-speaking environments. The speech synthesis feature can be used to convert written lessons into spoken words, making it easier for students to practice listening and speaking.

On the other hand, ChatGPT can be used to simulate conversation with the students. It can answer student questions, provide in-depth understanding of topics, and even help with some teacher tasks. The 24/7 access to support and guidance feature can be particularly useful for students who want to practice speaking English outside of class hours. The personalized recommendations feature can help students know what they should work on next, and the gamified learning feature can make speaking practice more fun and engaging.

By using these two tools in combination, you can create a comprehensive and engaging speaking practice environment for your students.