I currently run a server with plex to feed my media to my LG smart TV.
The server runs 5 HDD's, 1x dedicated for the system drive and 4x HDD's (2x 2TB, 2x 1TB) for the media, running Drivepool from Stablebit (best software purchase I have ever made!).
The TV sees the folders as you set them up in Plex (eg TV series, movies, etc.) so it makes browsing for files nice and easy from the connected devices menu.
I am also using sickbeard to organise the files, it has a brilliant rename and organise feature to keep everything organised in the right places from just dumping everything into a 'blackhole' folder that is accessible over the whole network.

I am wondering if a NAS box can take over from the server in this situation. My main requirements would be that the NAS would be visible to the TV using a sensible file /folder structure rather than a mile long list of files and a PC running sickbeard can access and alter the contents of the NAS drives over the network.

I haven't had a NAS yet and wondering if people who use them can give me any opinions as to what NAS would suit my requirements if any so I can do some more research.