A stable board with ALWAYS overclock with ease and perform well with multiple hardware stress benchmarks! Overclocking places more stress on the motherboard. A board with higher quality components that can handle higher voltage, current, and temperature will remain stable at higher FSB and Vcore. Remember that heat (current and voltage) is the number one killer of electronics.
Same logic applies to CPUs. All A64 3000 will run okay at 1.8GHz. However, those chips that can hit +2.6GHz will have higher reliability and stability in the long run at stock setting.
If a motherboard is bug-free for the first month of use, then it should provide many years of reliable service. A buggy "platform" will show up within a few days of use. The Intel platform is popular because it is the number one CPU vendor. PC vendors get a better discount when they combine the Intel CPU and MB/Onboard Video. Most PC enthusiasts would not use the INTEL board because there are many better alternatives.
Software conflict is the number one cause for system instability! I usually stay away from 1st generation board and BIOS. The vast majority of 754 and 939 boards from 1st tier manufacturers are very good to excellent in stability. These vendors deal with large volume and they cannot afford to deal with RMAs.
So who are the top tier MB vendors? Asus and ECS.