The difference between the 256bit and 192bit cards is very small to prefer one over the other.
The 1GB card does have more space for textures etc, so if you play games with high-res textures, or plan to use high res textures in Dolphin, having that 1GB would be really nice.
The 1GB card does have more space for textures etc, so if you play games with high-res textures, or plan to use high res textures in Dolphin, having that 1GB would be really nice.