I use one of the dodo juice bags, the second in Hou's post. I love it, lots of access to my kit and very sturdy. I've had zi-p style, but found them to get a bit annoying having to open and close them while working on the car. Also means I can keep the majority of stuff in one place, making few trips through the house with wet shoes. Here's a pic of mine.
There's plenty of pockets both on the inside and outside for microfibres, clay bars etc.. and the handle is very solid. Comes with a carry strap to make taking it about easy.