Network(s) Optimization

Got the modem/router up and running yesterday. It generates two wifi networks, a "regular" and a 5G per the names. I got the 30 second lesson on better range/slower speed vs less range/faster speed. The router will be located close enough to the TV that does 75% of the streaming in the house to use Cat5 to connect if I want to. 

Which of the three options would you pick for the TV?

Is trial and error the best way to decide on which "network" to use? 
Does anybody really notice a huge difference between the 2.4G and 5G?

Am I overthinking this?