On a whim, I listened to Dark Disciple over the past little while. I had read it previously, and had it ranked as my top novel. Finished it today.
I'm not sure it belongs at the absolute top of my list where I had it, but it's really good. The only thing that hangs it up a little are a few elements that seemed extraneous, and a final act that went a little too long. Notably, the Mahran race and Desh in particular served no real narrative purpose, and Voss's first return to the fold was very uneven and could have been compressed.
However, it's definitely one of the best arcs. A novel about the exploits of Ventress and Voss can't be anything but awesome. I soooo wish that the final season of Clone Wars had happened, as this would have been its greatest story.
Now listening to Heir to the Jedi, which I had previously read, and had at the bottom of my list. While it's not without its charms, so far it definitely belongs at the bottom of my list. The first person narrative really doesn't do it much credit at all.