The circuitry to determine that the contents of eax after test eax, eax are the same as before the instruction is simpler than the circuitry required to arrive to that conclusion for or eax, eax. For this reason, test is better.
Some compilers may have generated or at a time when it did not make any difference (before out-of-order execution), but it will make a difference with some out-of-order processors nowadays (whereas yet other OOO processors will be so sophisticated that they will recognize or eax, eax as truly equivalent to test eax, eax).
I couldn't find a reference justifying that some modern processors are actually able to infer that or reg, reg does not modify reg, but here is an answer claiming it is the case for xchg reg, reg.
