Chatfuel - Chatfuel is the best bot platform for creating an AI chatbot on Facebook.
Meya.ai - Build, train and host sophisticated bots.
Tars - TARS enables users to create chatbots that replaces regular old webforms.
Chatbots - Chatbots.org (BETA)
IBM Watson Assistant - Watson Assistant is an AI assistant for business.
Dialogflow - Conversational UX Platform. (ex API.ai)