I'm a big fan of the Myers Briggs test and its ability to help me understand myself and others better. I've taken it several times in the past 15 years and always it really enjoyable and interesting. I've also changed my personality type which has been fascinating. I was an ISTJ in high school and college, an INTJ in Peace Corps and I'm an INFJ now.
By better understanding my personality, I've not only made sense of what I am going through at different times in my life, I've also been able to attract things into my career and personal life that are a better fit for what I want.
I've taken a lot of tests, but here is my favorite one.
Also once you take it (bonus points!) you'll be able to see which character you are in Star Wars, Harry Potter, Lord of the Rings, Marvel Comics and more, which is always fun. You might be surprised who you are!