What type of laundry detergent do you use?

TinyPinkBug

Do you use powder or liquid detergent?  I was reading an article last week (can't find it now, someone posted it on FB) about the impact of cloth diapers on the environment being equal to that of disposables.  A large part of that was the laundry detergent.  That most ppl in the US use liquid which impacts the environment not only by the production and waste of the container (plastic of some sort, even recycled material plastic uses a lot of energy) but also the impact of the shipping of the liquid.  The study found that when using liquid, it was equal impact to using disposable.  It also looked into energy usage to wash (assumed air dry) as well as the water management. 

So I keep thinking about the powder vs. liquid.  Why do I use liquid?  Is it better?  Why not use powder?  It usually comes in cardboard containers, and is way lighter.  And if you use powder, what brand?  I am thinking I am going to make a switch this week.  I do so many loads of wash and I don't even CD.