I have s voice and google now, of course, but also downloaded cortana and hound. I am testing them. Nothing ground braking but so far I am not impressed with sound hound. The one thing its suppose to be great at is understanding your voice and complex commands. Twice I have tried to use it and it stumbled in key words. This is by no means any indication of the apps issues, I of course would find user error in my flawed experiment.
I haven't used any of these apps, but for a goof in the past. Keeping them active meant destroying my battery. So far I have been pleased with the note because I have kept most if not all features active all day. I don't yet have a car charger, or spare charger, so I have had to put it into defensive modes while traveling to make sure I still had battery. But that was because I was using pandora, maps and general use followed by note taker and such.