I have ONE cookie recipe that I've been using and tweaking for the last 3-4 years; I do cook a lot but it's mostly haphazard "Let's try doing this and see what happens!" stuff and a few basic dishes I like, so this may be my only real contribution to the thread.
2 2/3 cups flour
1/2 tsp baking soda OR 2 tsp baking powder
1 cup sugar
1 cup brown sugar
1 tsp salt
stir dry ingredients together, then add:
2 tsp vanilla extract
3 eggs
1 cup butter
mix, and add 8 oz chocolate chips if desired
bake at 350 degrees for around 10 minutes
I think the recipe may do better with a little more flour; I also tend to use heaping cups of both types of sugar because I have a sweet tooth

and I've occasionally replaced the vanilla extract and chocolate chips with hazelnut extract and nuts for a nuttier cookie.
Note: I only have 2 small baking pans for cookies, and the recipe's for making a huge batch all at once, so I usually put the extra in a muffin pan instead of waiting, and they turn out well that way, too, except the top caves in a bit so it ends up concave instead of round like a normal muffin.