I have been building PCs for quite a few years for a living (remember CP/M?). But this is only my opinion...
ASUS is one of the largest and most respected of mainboard manufacturers. Their products are almost always of superior quality to almost any other brand you can buy...and you will pay just a little bit more for the name ASUS as well.
That being said, like most manufacturers, ASUS makes mainboards at varying price points and with various chipsets. For stability and compatibility, I recommend mainboards with nVidia chipsets for AMD processors and I recommend Intel chipset mainboards for use with Intel processors.
I also note that memory is by far the most sensitive choice you can make when building a computer. For this reason alone, I recommend you buy your PCs already assembled in a well tested configuration. My shop is littered with incompatible memory modules... You can't even order the same memory parts and expect to get the same memory modules regardles of brand! Furthermore, it is almost never safe to mix dissimilar memory parts in a PC. Don't do it! If you have to, replace all the memory when upgrading.
I repeat: memory compatibility is THE key issue in stability of a computer. And frankly, I don't trust a new hardware configuration until a) after I've done a careful OS installation with the new configuration and b) it has run without problems in the field for some weeks. Be VERY observant of ANY glitches during OS installations when working with a new hardware configuration...they more often than not indicate memory compatibility issues.