Cadd...
They're all rather different bikes, actually. The Sirruses and the Coda are probably the most similar -- essentially hybrids, though the Sirrus really ahs more of a roadie geometry and spec. The Aurora is a low-end road/sport-touring bike, and the Nova is a cyclocross bike with touring bike manners. Of the bunch of them, I like the Nova the best, but thst's just because I like cyclocross bikes [for cyclocross] and drop handlebars.