I'm not much of an AC expert. From what I understand, it allows for greater bandwidth and range, yes, but it also operates on 5GHz band, which is less crowded. Although I though 5GHz was a weaker band, no? AC routers are more expensive, much like Wireless-N were when they were new.
What I was suggesting is to improve your access point with something like the Ubiquiti UniFi AP. It gives me full bandwidth on 2.4GHz Wireless-N in my entire house. I have a D-Link DIR-825 router, which was hot stuff back in the day. I even added a couple "long range, high powered antennae" to it to help with range. Didn't help. I considered Amped Wireless stuff, but they are expensive too.
Finally ended up using a Ubiquiti UniFi AP because we have success with them in my office. You can add multiple AP's very easily, so you can have one in different corners of your house, yard, whatever. Basically, you turn off wifi on your router and connect the UniFi to it. The router does the routing/dhcp stuff, and the UniFi does the signal broadcasting.
For me, I didn't need more bandwidth. I needed signal strength. I have a one story, four bedroom, 2400 sqft house and no matter where I am, I get nearly the same download speed as if I were hardwired in. YMMV
