I'm not sure what you mean by a "pH test"....are you talking these strips you dip or the color match tests???? Regardless, I don't think you can beat a pH probe that is properly calibrated.
I will also state that some make a big stink about pH....when little to no concern should be put towards it. Proper reef chemistry (alk and calc, assuming no major CO2 problems), will keep the pH were it needs to be. When my pH probe finally craps out, I'm not replacing it.