Salt and Saffron is definitely her finest, if you ask me. I did make it through Kartography because I'm academically very interested in the theme of map-making, but I didn't think the book lived up to its potential, and I skipped the fourth one altogether. But I'm really fond of In the City by the Sea. There's something really stark and authentic about it, from the tragedy of the opening scene to the realism of the characters. And, of course, Karachi.

I've been reading wonderful reviews of Burnt Shadows too, so will probably give it a try. :-)