1 / The healer
The class starts with a problem. The teacher may start with healing trauma or lower back. You take the class because you feel like crap and want to do something about it. Yoga is inherently positive so you should come out feeling better, if not different for the better. Music in this class is completely irrelevant. You may be sweating a lot or not at all. It depends if you deal with a 'shaman' or 'physical therapist'.
Why should you take a class with a healer? Because you have a problem and you want to solve it. It is quite impossible to enjoy life in general if you are in pain.
2 / The educator
The class starts with physical or alignment focus. This class feels more like an anatomy class, but it is more fun because you get to move and touch yourself, appropriately of course. You will learn proper alignment and may get little obsessive about it in your practice and in your teachings. You should walk out of the class more knowledgeable. Knowledge is power.
Why should you take a class with an educator? Do you want to know everything about psoas, how it affects your life and what poses alleviate weak/tight psoas? Then take this class.
3 / The joker
The music is loud. You are sweating like crazy, barely catching your breath and barely catching the instructions too. BUT it is so fun to be there. Alignment and spirituality are out of the window, but the music is great. This class is a great stress buster. It fits great into your 9-5 life and not surprisingly enough, it is scheduled right after your work.
Why you should take this class? When you want to forget about your work, wife, husband and whatever. You just want to be entertained and have fun.
4 / The experience designer
You walk out of the class transformed. The sequence is varied, but not detailed. The pace is medium; you do not have time to space out, but you do have time to take a deep breath. Spirituality is definitely involved, it gets heavy at the beginning, but light at the end. Music is spiritual and electronic to throw your mind into a different dimension. You will walk out with some sort of message about life.
Why should you take this class? Because life is worth living and this is a proof. You will feel like you just went on a great trip, visited museum, or ate at a fantastic restaurant.
5 / The politically correct Vinyasa girl
You may not chant OM because she does want to offend your belief system. You will get a well-rounded practice that is not too boring nor too intense. You go to the class because you get a great workout. The teacher is just so nice. She may not be funny or engaging, but she wants you to take care of yourself. She did gymnastics as a child, studied dance or psychology or marketing at college and teaching yoga just feels like a natural extension of her dancing career.
Why should you take this class? If you do not want to ponder about the meaning of chants, Indian Goddesses, complicated or detailed poses, then take this class. It does not rock the boat, but it still makes you feel great.