Here. have a time-line. The notes are added in by me, based upon my interpretation.
I'd put Lords of the Sith and Tarkin at the top.
Lords of the Sith is just pretty crazy, you learn a little more about Sidious and D. Viddy's relationship and are treated to a feast of awesomeness.
Tarkin is for my fellow Empire sympathizers, it's a fun read, and makes you respect the Grand Moff. This also explains why Vader seemed to respect Tarkin in the first movie.
Dark Disciple is the one that came out of the blue for me, I wasnt expecting to enjoy it but I did. It follows Ventress and another Jedi trying to survive in the early days of the Empire.
I have yet to read Battlefront.
Give it a shot at least, if you enjoy Twilight Company, you might enjoy Tarkin as well. It really shows how he came to be such a cold motherfucker.