Plisson for L'Occitane came out before RR Plissoft, it wasn't as expensive as a Plisson and more expensive than an RR.Razorock is a knock off Plisson and came out with Plissoft before any other vendors really had anything close. Plisson makes a good synthetic now because Razorock had a excellent product(possibly better) and they had to regain their market back just like Simpson synthetics had to come out with a good version to compete with every one else.
I like Plissoft but Yaqi lately has some stellar brush products at a reasonable price and excellent lathering tools IMO.