All manufactures have their own labeled stuff and most is generic rebranded something. Honestly, I didn't realize that WS was that specialized TBH.
As you're new to the Toyota side of the fence...
Most of us hold Toyota OEM fluids in high regard. I would not consider them generic rebrands. From the few objective tests results available, Toyota fluid are some of the best on the market. Basically saying it's hard to do much better, and likely to do worse, as sometimes even high quality 3rd party fluids can have odd compatibility issues as they've not been fully validated like OEM fluids are.