I work for an ISP and CATV provider, on the wifi front, we run into our worst trouble calls for streaming problems dealing with Roku loaded tvs. The materials used in their craftsmanship are very sub-par to be dealing with the types of wifi connections we demand now days. My recommendation would be to buy a better TV and get a Roku stick if that is the route you wish to go.
Our best devices for streaming are any hubs, like apple tv. These hubs sit out in the open, or in an open compartment in an entertainment center and can receive a much better signal from your router this way. This greatly improves your picture quality while streaming. You can also achieve better quality out of your firesticks by purchasing a short HDMI extension cable and getting the stick itself located out away from behind the TV. Flat panel TVs are great reflectors of Wi-Fi signals, thus blocking the signal, or degrading it, to a point where you have streaming issues.