Hmmmm, I don’t know my sticks well enough to tell you for sure, but I think it’s a Happ Super. The bat is sort of short and chubby compared to the bats on most of their other joysticks.
I think you would be able to see a bit of silver (bare metal) shaft on a Sanwa JLW, but I’m not 100% sure. It would also have a looser, softer spring unless they specifically changed it for a harder one. However, the stick’s movement would be square (where you can feel the 1,3,7,9 corners and 2,4,6,8 are flat perpendicularly) as you described.
The Super is a decent stick. Most players prefer the Competition over it, but as always its just a matter of preference, some some people swear by the Super and the Super alone. This thread will explain the differences between the four main models of Happ joystick.