I don't particularly care for the 460. It's too weak to game at 1080p, and cheaper cards can handle lower resolutions just as well. It has the same problems as the HD 5830 did. The additional cost didn't match well with additional performance.
The 460 is definitely an excellent choice when a second is added in SLI. However, AMD chipsets don't natively support SLI, which can cause probelms. The chipsets that have built in support often cause compatibility issues with other parts. Given that the only way to avoid these issues is to buy an Intel CPU and chipset, which are completely out of budget, I can't come to recommend the 460.
They're basically equal in quality. I tend to land on the ASRock side on the more budget builds because they tend to pack in a few more features for a little less. Also, ASRock is the discount side of Asus, which is one of the top two board brands.