Router/Mesh System Question

I currently have the basic 200 MBps Charter Spectrum plan. I've got a Netgear Nighthawk that I have had for approximately 3 1/2 years. During the Christmas holidays, I was off of work and I would notice that the internet was buffering a lot and I was running slow speeds. On a good day, I would be pushing 150 MBps. This past week I was anywhere from 0-120 when I noticed streaming problems. I called Charter and had a technician come out. The guy seemed pretty knowledgeable and actually said that he has a Nighthawk at his home. To begin the troubleshooting, he took a cheap Charter router from his truck and connected it. He run the speedtest and it came back at 197 MBps. He run it again and it come back at 206 MBps. He connected the modem to the meter that he uses to test speeds and it came back at 229 MBps. He told me that it looks like my Nighthawk is limping along and I would probably soon need to replace it. He made a few suggestions. He said that I could rent the same cheap router that he used for $5.00/ month from Spectrum. He also made the recommendation that if I wanted to replace my Nighthawk with another one, then I might want to think about a Mesh system. He told me I wouldn't have to worry about any connectivity issues or slow speeds with a Mesh System and he recommended the Google Nest system. I have heard about Mesh systems before and I began looking at them yesterday. I'm not an internet guru but, the basic concept of the Google Nest system made a lot of sense to me especially if the 3 pack is close to the price of a new Nighthawk. I'm asking for a little help deciding which direction I should go. Should I go with the cheap $5.00/month Charter router that was pushing basically 200 MBps, replace with a new Nighthawk, replace with the Google Nest system, or something else? My wife works from home so she needs to have reliable service. I stream TV and I don't want to have any problems during a ballgame. My kids stream YouTube, Netflix, etc. We don't have any gamers so I don't need anything to push that much. Any advice that you can give me is greatly appreciated. I need to have something in place before Saturday because I don't want to take the chance of having bad service during the game.