What do I use as power steering fluid

I am going to remove and replace the old power steering fluid in my mini van but can't seem to find out exactly what type of fluid I should replace it with. I know on the shelves there is "power steering" fluid but I am also being told to use transmission fluid. Also I am having some issues with sluggishness and was looking something like Sea Foam to clean it out or Lucas Stop Leak/Conditioner. So what is the right answer in the type of PSF is best for my mini van with high milage.