ER7206

TP-Link Omada range has gateway routers that would work very well, and can work in failover or load-balancing modes. ER7206 for a gigabit WAN, or ER707 for 2.5Gbps WAN https://www.omadanetworks.com/uk/business-networking/omada-router-wired-router/

I would resist using multiple routers. You may run into problems with rogue DHCP and duplicate IP addresses unless you do a ton of configuration and have some level of control over what people plug into the network. There will be many recommendations for this situation, but here's how I did multi-wa

I second this. The TP-Link Omada is a prosumer range. Personally I have two WAN (broadband) connections and I'm currently using the ER7206 to do exactly what OP is after. It can handle three connections. The ER7206 Multi-wan router (gateway) has load balancing, and also has a Application Optimized R