Hmmm, good question.
My first motherboard was rock solid and let me OC a Athlon XP 2200+ Tbred-B up pretty damned high. I'm sure if I logged into the 3D Mark database, it would still have my clocks.
My favorite board though, would have to be the DFI LANparty nf4 board I had for the Athlon 64. UV...