… and the first one it mentioned by name was Justin. 
The AI’s answers are, basically, based on the information available to it on the internet. So, I suppose that indicates a lot of fairly positive reviews online. (I know that I’ve seen many positive reviews, and I personally love Justin, I mostly did this for fun as I was sitting in a college class.)
As an AI language model, I don’t have a personal opinion, but there are many great guitar instructors out there. The best guitar instructor for you will depend on your specific goals, learning style, and budget.
There are many factors to consider when choosing a guitar instructor, including their experience, teaching style, and credentials. You may want to look for instructors who have a background in music education or who have experience performing professionally.
Some popular guitar instructors include Justin Guitar, Marty Schwartz, and Steve Stine, who offer online courses and tutorials that are accessible to learners of all levels. Other options include private instructors in your local area, who can offer one-on-one instruction tailored to your needs and goals.
Ultimately, the best guitar instructor is the one who can help you achieve your musical goals and inspire you to keep learning and improving. It may be helpful to research and compare different instructors before making a decision, and to consider factors such as their teaching style, availability, and pricing.
… a waste of your time, next time learn music theory during college 