Asus has more of a higher end reputation, Sapphire is more of a middle to lower end reputation, that's at least part of why Asus products can cost more.
The 560 is an entry level card, so I would not pay extra for one. The ROG series is usually one of Asus's higher priced models. Unless you want the things it has, like RGB lighting or whatever, then I would not pay for that. Asus offers lower priced models if you'd still like to buy Asus. Same with Sapphire, look at their entire linup and decide if the more expensive ones actually have what you want and are willing to pay for.