One bot to rule them all? Not likely, with Apple, Google, Amazon and Microsoft virtual assistants

It's no wonder titans of tech are locked in an epic battle of the bots, racing furiously to produce the best virtual assistant. Thanks to the sudden acceleration of artificial intelligence and advancements in speech recognition and big-data storage, the technology behind virtual assistants is rapidly spreading from phones to cars and homes, and the truly useful helper is approaching fast. The four giants are fighting for the biggest share of a market expected to grow to $12 billion by 2024. "There's a tremendous amount of promise for these agents to help and assist with many different tasks that we face every day," said Ross Rubin, principal analyst at Reticle Research. "The more the agent can help you with, the more value it holds."