Virtual-assistant technology at the heart of any smart speaker changes depending upon the manufacturer. From Alexa to Siri, Google Assistant, and others, each brand has strengths and weaknesses. Some are better at free-form voice commands or facilitating online shopping, while others excel at web-based searches for information. The number of compatible third-party devices also varies widely. So, keep this in mind: Like cordless drills and politicians, you are not choosing a tool, you are choosing a platform.