haven't heard of studiobox, but for modern general sound library nothing beats digital juicer in terms of price/quality/quantity (
Digital Juice Sound FX Libraries by Digital Juice)
i only have the first out of three boxes, but i reach for it as often as i reach for 6000. it is greatly organized, sound quality is more consistent than that of sound ideas, and the ambiances are pure, great for layering....
i will definitely get the other two; can't recommend it more.