it all depends on what you define as better..
if you mean performance, then going by Via's track record, the AMD solution will be the better performer.
going by reliability, we've had alot more experience with the Via chipsets, and we know AMD's chipsets are somewhat tricky sometimes with generic components, in this case, Via wins IMHO. though there are some odd problems I've heard about with soundcards on Via chipsets..
the difference between the Via KT133 and AMD's 750 was that the 750 wasn't socket. that pretty much kept it from competing (AMD says they don't want to be the chipset maker). With the 760, I don't know what's going to happen to make it obsolete. it can't be the southbridge, becuase the 760 is pin compatible with every Via southbridge today (probably tommorow, at least for the short term).
what could it be? will Via somehow impliment an Asynchronous memory clock? I doubt it. AGP 8x? nope, I don't think so.. real support for AMD CPU's running with a 166mhz-200mhz fsb? doubt it, but hey, that's the only thing I can think of! it sure would be a killer chipset if that happened.. the problem is, considering Via's track record again on performance, it TAKES an extra 33mhz to beat the competing AMD chipset.. or at least, it did when it came to the 750 and KX133. no accurate benches can be made when considering the 750 compared to the KT133, unless you have a very rare Slot-A T-Bird.