Alethea AI is a top contender, with CharacterGPT V2, a text-to-character AI engine that generates interactive AI characters. You can fine-tune and train AI characters for different purposes, like digital twins, virtual assistants and even AI collectibles. The company also offers a collection of decentralized smart contracts to manage ownership and governance of AI characters, so it's a full featured service for building and profiting from AI personas.
Another good option is Avatar.One, which lets you build your own AI girlfriend with the personality and behavior you prefer. It can handle natural-sounding conversations and a variety of interactive situations for a very engaging and immersive experience. With customizable 3D avatars and strong privacy controls, Avatar.One is a good option for people who want to form a deeper digital relationship.
For a more general-purpose service, check out Kamoto.AI. It lets people create, train and monetize their own AI personalities in a variety of domains, including gaming, education and health. The service offers licensing deals with celebrities and influencers, too, which opens up a new level of interactivity.