YS Tech has fans that can argue with most Deltas, but none to my knowlage that can argue with the FFB series or it's derivatives like the QFR series - the YS Tech lines are designed to be competition for the Delta AFB "low backpressure design" series and it's derivatives.

 I'm not aware of anyone else that even gets CLOSE to 200cfm at the kind of backpressure the FFB/QFR/etc lines are designed for in a 120mm format.