The decision on which state in which to take the bar is highly personal and depends on a variety of factors. When making your decision, remember that (with very limited exceptions), you will only be permitted to practice law in the state in which you take your exam. So, if you are planning on practicing law in the US after taking the exam, it is a good idea to take the exam in a state in which you would like to live or work.
On the other hand, if you are not planning on practicing law in the US, you might instead base your decision on the simplicity of the state’s requirements. For example, New York is popular among international students, while California is considered to be one of the more difficult states in which international students can obtain a qualification.

The bar exam is taken in several parts over at least two days.