The very best I have ever used is a product from Dylon fabric care called "Travel Wash"--it comes in a tube and I think is from Europe (maybe the UK?). It doesn't oversuds, but gets clothes about as clean as you can get them in a sink, and...very important...is much easier to rinse completely out of the clothes than regular detergent or even Woolite. When not travelling, I use it around the house for my handwashables rather than Woolite. I'm sensitive to many laundry detergents including most powders, but this tube product doesn't make me itch.

In the US, you used to be able to order this from Magellans or TravelSmith websites, they called it "Getaway Travel Wash" or similar. Not sure if they still have it.