ElevenLabs and Sierra.ai are prominent conversational AI platforms, each offering distinct advantages for creating advanced voice agents. ElevenLabs focuses on developing its own text-to-speech (TTS) and speech-to-text (STT) models, which provide benefits in terms of latency and voice quality, and supports over 70 languages, making it suitable for multilingual applications. In contrast, Sierra.ai specializes in crafting AI agents that align with a company's brand and can automate business processes, offering integration with external APIs and telephony systems. Both platforms allow for extensive customization and knowledge base management, enabling the creation of domain-specific voice agents. While ElevenLabs provides more detailed voice customization options, including the ability to create voices from text prompts, Sierra.ai emphasizes real-time support and personalized agent development. Data retention policies differ, with ElevenLabs offering customizable options, whereas Sierra.ai focuses on data privacy without publicly disclosing specific retention periods. Ultimately, the choice between these platforms depends on the specific needs and goals of the user.