There are several reputable online courses available to learn AI, and the “best” course depends on your existing knowledge, learning style, and specific goals. However, here are some highly regarded online courses that are popular for learning AI:

1. “Machine Learning” by Andrew Ng (Coursera): This course is considered one of the best introductions to machine learning and covers the fundamentals of AI algorithms, including supervised learning, unsupervised learning, and deep learning. It provides a solid foundation for understanding AI concepts.

1. “Deep Learning Specialization” by Andrew Ng (Coursera): This specialization consists of a series of courses focused on deep learning, a subset of AI. It covers topics such as neural networks, convolutional networks, recurrent networks, and deep learning frameworks. It is highly recommended for those interested in deep learning and its applications.

1. “Artificial Intelligence for Trading” by Georgia Tech (Udacity): This course is designed specifically for individuals interested in applying AI to financial markets. It covers topics such as stock trading, portfolio optimization, and building AI-based trading agents.

1. “Natural Language Processing” by Dan Jurafsky and Christopher Manning (Coursera): This course focuses on natural language processing, which deals with the interaction between computers and human language. It covers techniques for text classification, sentiment analysis, language modeling, and more.

1. “Deep Reinforcement Learning” by Pieter Abbeel and John Schulman (Udacity): This course delves into deep reinforcement learning, an area of AI that combines deep learning and reinforcement learning. It covers topics such as Q-learning, policy gradients, and deep Q-networks.

1. “Applied Data Science with Python” by University of Michigan (Coursera): While not solely focused on AI, this course teaches various data science concepts and tools, including machine learning algorithms and their applications. It provides a comprehensive understanding of data science, which is crucial for AI.

1. “Introduction to Artificial Intelligence” by Stanford University (Coursera): This course offers a broad introduction to AI, covering topics such as search algorithms, game theory, logical reasoning, and knowledge representation. It provides a good overview of the field.

Remember that AI is a vast and evolving field, so it’s important to continue learning and updating your knowledge regularly. Additionally, it can be beneficial to supplement online courses with practical projects and real-world applications to gain hands-on experience.