Is Plex just for serving media to your TV or is the plan to use it for tablets, mobiles, etc.
If just for your TV then I'd think about using Kodi rather than Plex with Kodi on a Raspberry Pi or cheap Android stick. No transcoding is necessary so a smaller, cheaper, less power hungry NAS can be used.
Personally I prefer the Kodi interface over Plex and find the setup easier (although it may be because I've used it for years).
If you're planning to get media over phones and tablets and the like then setting up Plex once is probably easier.
I have been using that up till a few months ago, but then switched to plex for the very reason you mention, watching over mobile devices. Also found remote access easier over plex.
Is Plex just for serving media to your TV or is the plan to use it for tablets, mobiles, etc.
If just for your TV then I'd think about using Kodi rather than Plex with Kodi on a Raspberry Pi or cheap Android stick. No transcoding is necessary so a smaller, cheaper, less power hungry NAS can be used.
Personally I prefer the Kodi interface over Plex and find the setup easier (although it may be because I've used it for years).
If you're planning to get media over phones and tablets and the like then setting up Plex once is probably easier.