There is no "best" but... (Score 1)

In my opinion, you're not going to get a great solution for less than the cost of the replacement network card. The Roku Ultra will do everything you want -- only it will cost $99. It's powerful, supports 4K HDR properly, does Amazon, YouTube, and Netfilx well. Plus it plays media off of USB and MicroSD, and does both Wi-Fi and Ethernet. My only grumble is lack of support for exFAT on removable media. It also presents as a Chromecast if you want to use it that way (I also have a Chromecast Ultra so I don't). Nearly everyone deploys apps for the Roku first, so chances are you'll find a Roku "channel" for anything you want to stream. Fire TV does the best job of supporting Amazon content, and the gen 1/2 boxes were overpowered so they were super responsive on the UI. But its transformation into a Chromecast clone is unfortunate.