Considering the audience: Get whatever x86 (arm if you have a more enthusiastic vibe and don't mind some independent research) hardware, install your Linux/BSD distro of choice (it doesnt need to be a "router" distro in case youre already handy with some other base system. setting up from vanilla can be easier than getting into idiosyncracies of openwrt/pfsense/etc) and configure it yourself. It will be valuable and useful even if your ISP requires their own gateway in the middle. Get 2 of whatever it is so you have a spare/staging ready if it becomes necessary later.

Intel NICs are generally preferred over Realtek if available.