Illumina (NASDAQ: ILMN) and Bionano Genomics (NASDAQ: BNGO) might both make gene sequencing devices, but as investments the two couldn't be more different. Whereas Bionano is a new entrant to the market and still has a lot to prove to its investors as well as the scientific community, Illumina is the top dog that's fighting to maintain its position. Bulls argue that Illumina is the better gene sequencing stock because in some sequencing markets, it's basically the only option in town, particularly in the all-important market for next generation sequencers (NGS).