The tests that seem the easiest are usually best. I have seen a test that divided people into something like 14 different categories. Stick with one of the tests that has four categories. They might be referred to as Melancholy, Choleric, Sanguine, and Phlegmatic or they might be called Thinker, Senser, Feeler, and Intuitor. They are roughly the same, with a few differences.
Many people test as roughly equal between two or even three categories.
The test-givers always seem surprised when that happens, but I've seen it over and over again. Those people are usually remarkably easy to get along with, incidentally, because they tend to automatically adapt their manner depending on who they're with. These things really do help, even if they are mostly based on some theories of Jung, a noted head case, oops I mean head doctor. If nothing else, they can help pinpoint your weaknesses, which you can then work to improve. Having one half of a couple take one of these tests can be dangerous, unless that person is willing to perform all of the behavior-modificaion, knowing that the other person won't.