Well I've never had any problems with any of the Asus products I've bought. Though I haven't bought any of their full products, but I have bought multiple motherboards, and video cards from them as well as a wireless card and haven't had any issues with them.
I'm not aware of the BIOS problems you are referring to.

As for Sager... its not a company I've heard of (well I think I remember a similar name from a related industry, but I've never seen any computer components or products from them). The specs look pretty good, but I couldn't say anything for quality.