Tein: Great Japan quality. If bought through Fulcrum, they are re valved/sprung for Australian roads.
G4 Racing: Cheaper quality, not sure where they are made. Will not perform as good, in the long run.
Even though the SK gb kit are great, i still prefer my adjustability. I like the thought of adjusting the stiffness for various roads, events, conditions, etc. And the Tein EDFC makes it soooooooooooooooo much easier