Chickpeas (and personally, also coriander) is probably the only constant ingredient in falafel. There are so many different recipes that you will never eat them exactly the same way.
Yesterday I decided to make (1 can of chickpeas will be good for 8 normal size falafels) them with 1 teaspoon of curry, 1 teaspoon of cumin, 1 garlic clove, 1 shallot, ½ bunch of coriander, 1 egg, and some salt. Mix everything in the blender and taste. Roll the falafels and put them in the fridge before baking time. I know that frying them is the traditional way, but I prefer to bake them in a really warm oven (200°) in a oiled oven dish, or even on baking paper. It will take 20 mins and they will probably be a bit drier, but less greasy. Serve them with low fat Greek yoghurt seasoned with pepper and salt (a little bit of lemon zeste will make the sauce even fresher).
Eat falafel as an appetizer, or serve them with a colorful salad as first course.