I use a "green" product called Seventh Generation. It smells pretty and is ecologically sound. I do pay a bit more for it than I would a commercial brand, but I buy the container-full every few months and then re-fill it every couple of weeks out of bulk (of the same detergent) in my local co-operative store. Less mess, less waste of bottles
I have always been a fan of "Free and Clear, ALL". It is basically just regular ALL brand detergent but the free and clear indicates no dyes or perfumes. This is great for anyone that has tender skin or many allergies. Currently I believe my wife is using Tide but I cannot remember exactly.