From what I heard from people who deal with all 3 voice assistant products, Google has hands down the best vocal recognition, Amazon the best logic.  Siri is purportedly lagging behind in both areas.  I can say that both Google and Amazon have been relatively reliable on the first shot, with Google a bit better.  Haven't had a single misinterpreted command with my roughly 2mo old Echo sofar.  A few quirks, but works quite nicely.