Definitely better than Google. It's a big step in preventing a monopoly for one thing. All twitch really needs is the financial backing to improve its infrastructures and not get demolished in court in the inevitable lawsuits it will face and Amazon can do that as well as google. And unlike google, not everything amazon touches turns into actual shit. That last one is a big plus.
This is essentially my thought on it too. If Google snapped them up it would have given Google a dominating lead on internet streaming across the planet so Amazon buying up Twitch means more competition. Whether that harms or benefits Twitch in the long run remains to be seen.