I think it is very unfortunate that "Lost Stars" hasn't been given the attention of Aftermath. I have just finished both books, and Lost Stars was one of the best I have in a long time - probably my favorite so far out of the new canon (I enjoyed it more than even Lords Of The Sith). I couldn't put it down - Lost Stars was everything Aftermath wasn't.
I liked Aftermath as a "snap-shot" of the post Battle-of-Endor galaxy. I think in the EU people tended to overlook how the Rebels barely won that battle, and they weren't in a position to go fully toe-to-toe with Empire and have a serious chance of winning (Remember Ackbar commenting how they wouldn't last long against those Star Destroyers - and that was the largest fleet the rebels could amass at that point). You could almost just read the "interlude" chapters that show events around the galaxy, and just the last chapter or two of the story. I found more of a "6 o'clock News" view of the galaxy as opposed to a really engaging story.
Lost Stars in contrast is more of a romance novel that looks through the eyes of "average joes" in the Rebel and Imperial forces and we get to experience the events of the Original trilogy and shortly thereafter through their eyes. I found the characters in the story much more engaging (to the point where I had to put in the DVD's and re-watch some of the battles - not that I need much excuse to watch Star Wars...) and relatable.