Is GL.iNet Flint 2 (or 3) better than an ISP router/modem or most Asus/TP-Link routers for privacy/anonymity/security?

First, nothing is perfect.. Every product has pros and cons. That said, having some control is better than none, so I’d choose a router I can manage (for example, one running OpenWRT) rather than relying solely on the ISP-provided device.