Depends on your budget.
Personally i'd go for synology or qnap - my personal preference having played with other devices and failed to easily get them to do what i want - ie without having to hack the hell out of them!
Synology DS509 is what i settled on a good couple of years back - and never had any problems since.
So far anything i couldn't get it to do out of the box has been added in the future with updates from synology so now i'm using it without hacking in any form to download through rss feeds, torrents, serve video/audio to my DLNA tv, galaxy tab, iphone and other pc's without much tweaking...
They are on the more expensive side, but in my experience, worth paying if you will be using it as the core to your AV in house...
