To be honest, it really has to be depending on your ISP and what package they are offering you.
I'm using wireless N and it's pretty fine for the stuff I need to do.
However, if you do a lot of streaming, then go with AC. Again, it depends on what package/speed is offered by your ISP.
Also, how strong is your wireless signal to your router? Sometimes, that can affect it too. You can just purchase a WIFI Extended if signal strength is an issue.