I recently got a Dell Optiplex XE3 second hand and set it up as a home server. It's working great and I wanted to share some info on it in case it's a helpful reference for other people's home labs.
The Dell Optiplex XE3 tower is configured with a i7-8700 (6c, 12t), 32 GiB DDR4 RAM (2 sticks), 2 2.5" SSDs, and 1 M.2 NVMe SSD. I installed Debian 12 minimal and services are deployed via Docker. I'm currently running 20+ containers, with some of the heavier containers being Jellyfin, Nextcloud, Paperless NGX, Home Assistant, and Immich. I haven't performed any software power optimization; it's just a standard Debian install. When idle with no significant load on the containers, power consumption is 14-15W measured with a Shelly Plug. While not fantastic (my previous server had 6W with similar loads), it is lower than I expected and is quite reasonable.
Overall, I'm impressed with this system. It currently has 4 unused PCIe slots, 2 unused SATA connectors, and 2 unused DIMM slots so it has solid future expansion. I have it laying on its side on a rack shelf and it takes up about 3.5U of space in my rack. While I wish it was smaller, fanless, had lower idle power, and had 2.5G Ethernet it has better idle power than I expected for its configuration and options for future expansion.
How "big" are your movies and tv shows? If they are 4k UHD remuxes then Nvidia Shield Pro or Apple TV 4k behind a firewall to block external internet is your best option for performance, usability, and privacy. You will want to ocassionally allow it internet for software updates. Kodi, a mini pc, raspberry pi, etc. would be more private but you trade off a seamless remote, easy interface, and streaming codecs (e.g., dolby vision).