The best features of Fortinet FortiGate include selling a perpetual license as a primary benefit, and the license cost is not much compared to Cisco, Meraki, or HP.
Feature-wise, I can rate Meraki over Fortinet FortiGate a seven or eight since they have micro-segmentation and application routing. They can detect real-time threats with FortiGuard, which is similar to Palo Alto. Now they are implementing AI features, and I recently went through the demo, which is amazing.
The main benefits that Fortinet FortiGate brings to customers include that if you're going for a single fabric with core switches, access switches, and APs, compared to legacy Cisco or Aruba, te Fortinet FortiGate does not require a controller for the access points. Fortinet FortiGate itself acts as a controller.
Similarly, they have FortiLink, which connects all appliances in a single stack, allowing maintenance with FortiManager and FortiAnalyzer. In comparison, Cisco requires a separate controller for SD-WAN and Nexus ACI controller, and other things require a Cisco DNA controller. However, with Fortinet FortiGate, it's simple to maintain using FortiManager and FortiAnalyzer, thus being very much easier and cost-efficient.