Lost Kitten is definitely one of the highlights of the album. The vaguely glamorous feeling of decadence and charmingly disdainful sarcasm Metric learned to hone throughout the years is sharpest in that one. In fact, all of Synthetica feels like the band finally found a perfect balance between their intelligence and their pop sensibility. Love Youth Without Youth and Speed the Collapse as well, but all the songs are quite good.
EDIT: Also, "I was looking for a hooker when I found you", given context, is one of the best lines in an album chock-full of juicy one-liners. It definitely feels Emily Hayes' lyrics-writing hit a good new height here.