Which of these cybersecurity giants is a better investment?Fortinet (FTNT -0.85%) and Zscaler (ZS -3.37%) represent two different ways to invest in the expanding cybersecurity market. Fortinet provides a wide range of endpoint security services for on-premises, cloud-based, and Internet of Things (IoT) devices. Zscaler is a smaller, faster-growing provider of cloud-native "zero trust" services that treat everyone, including a company's top executives, as potential threats.Over the past 12 months, Fortinet's ...