Brave: This is one of the safest browsers on the market today. It blocks privacy-invasive ads & trackers. It blocks third-party data storage. It protects from browser fingerprinting. It upgrades every webpage possible to secure https connections. And it does all this by default.
LibreWolf: It is designed to increase protection against tracking and fingerprinting techniques, while also including a few security improvements. This is achieved through their privacy and security-oriented settings and patches. It also aims to remove all the telemetry, data collection and annoyances, as well as disabling anti-freedom features.