Here are some quotes by Srila Prabhupada on the Four Vaisnava Sampradayas. They are organized first by quotes about all four in general, and then by individual line.
"There are four Sampradayas from the beginning of the creation. One is called Brahma Sampradaya, and is coming down by disciplic succession from Brahma; another Sampradaya is coming down from Laksmi, called Sri Sampradaya; another is coming down from the Kumaras, they are known as Nimbarka Sampradaya; another Samprada