I want to replace the router/modem Comcast with a high quality for streaming

@jond 

Congratulations, great improvement.

After switching to their router/modem (from a top of the line Netgear Nighthawk) last month we final got the 1,200mb we have been paying for for years. Last night the movie kept stoping as the speed was at 12mb and dropped to three or less repeatedly. 

@mitch2

Glad to hear it. See how long you have that speed.

Xfinity would not touch my Modem / Router.

Also check your billing for extra charges. They charged me $100 to put in their router and a couple mystery charges. No cost other than the monthly charge told to me by the technician.

@mitch2 “…that will hopefully provide the speed I am paying for. ”

Good luck with that. Bird dogging Verizon to get what you pay for is a full time job. When you don’t get it with a third party modem / router they will claim it is your router. 
 

Don’t get me going.

@KR4 I am not recommending in line extenders! I am recommending wifi extenders.

OP, yes streaming has come a long way. My streaming system sound quality is the same as my vinyl playback… and both are very very good and in my investment level are about the same cost.

After spending years with my own router / modem… the most recent, the $500 versions… and constantly having trouble with them basically caused by Verizon, I finally gave in and had them install a Verizon router. I have good quality Aurrender streamers and none of the three or four different routers, including the Verizon made any difference of sound quality. At all. However, Verizon can no longer point to my modem / router and say, “it is your problem. I can’t trouble shoot your router”.

I recommend sticking with Verizon’s box and upgrading your streamer if you want better sound. 
 

I have an outstanding main system and headphone system (see my profile)… that sounds like it is hardwired… but is using wall wart extenders.