Features to consider:

• Strong ability for technology to determine user intent. Some technologies do not robust artificial intelligence (AI) and force you to design keyword-based recognition methods instead of natural language conversations.
• A graphical user interface to set up and modify the chatbot conversation. Many chatbot applications can be continually improved as you monitor user conversations. Most improvements are content-based, not technical. Requiring programmers to implement content changes can slow down updates.
• Easy deployment. Some technologies require programming to set up the chat interface that end users will see and interact with. Some technologies are designed to work with chat interfaces like Facebook Messenger, Slack, etc. and may not work on websites or other systems.

No Programming

Botsify

Chatfuel

Some Programming

IBM Watson Assistant

Amazon Lex

Mostly Programming

Google Dialogflow

All Programming

Microsoft Bot Framework