I have to re-test the Intel-DX4 but from what I remember it is faster than the AMD-DX5 at the same clock speed. Can't comment on the stability aspect but overall the Intel part seems superior. The Pentium line unfortunately sabotaged the dreams of a 133 or 166mhz version of the Intel486 core.
I don't think Intel DX4 is faster than DX5. There are some benchmarks on the forum already, BTW. If you look at the "overall performance" chart in the second post, the AMD comes out around 20% faster.
Still, DX4 seems to be native to all VLB Socket 3 boards that support 3v CPUs, while AMD 5x86 is mostly supported by PCI boards.