Gaming router or extender?

More details are needed Shawn. Reason I say that is routers broadcast strength is set by the fcc. most are going to cover roughly the same area. they might have a bit different performance but in my experience, their actual broadcast covers the same. 

so how big is your home? Sq Ft. 

What is your interior walls made of? some materials block wifi better than others. 

Is it not hitting that deadspot at all or is it just slow? 

What speeds do you pay for? 

I'd also not recomend just "adding a nighthawk and maybe an extender" with your apple device. You can do that but you'd want the nighthawk in AP mode or you'd be in a double nat with the time capsule. also, the standard extenders drop throughput in half and increase latency. That's not good for gaming. The tri-bands can help with that because they dedicate one of the wifi radios just for router---extender communication. 

If your home is big enough, you might have much better performance, coverage by investigating the Orbi Tri-band setups. I'd avoid the dual band ones if you're gaming. I know amazon has been having renewed versions that have went on sale on/off over the last couple months for a pretty good price.