You should always think about the linux courses and the company that will be teaching them. Thus choosing COMAT is the best option as it has the best teachers and they have the necessary experience to show you what needs to be done. They would also tell you about some real life scenarios that they faced and how they dealt with them.
You want to be taught by the top teachers who would have the life experience and first-hand knowledge of what they can do. They would be able to teach you tricks that you might not already know of and much more.