Its tough to tell without more info.
1. who's your isp?
2. What modems are compatible with your ISP? That's the key. Many isp's only certify certain devices to work with their services. its why its a good idea to check with them to see whats compatible with their service. I would recommend going with a docsis 3.1 device.
Ok so another question. Why buy the pro gaming router when you’re already buying a really good modem? Is the gaming router worth it if I’m using LAN anyway? I want my internet to stabilize and not spike and to get my ping down to the 40 or below range.
take a read. Some find benefits. Some are able to customize their current routers to get them the same results as a gaming router. A lot depends on your capabilities.