No, the Omnisphere plugin isn't necessarily better than the Serum VST plugin. They both have unique sounds and features that can be used to create different types of music. It ultimately comes down to what kind of sound you're looking for, what kind of music you want to make, and your available budget. Serum costs $189, while Omnisphere is almost double the price costing $500. The Spectrasonics website says Omnisphere comes with 14,806 sounds, while Xfer Serum has 450 presets and 144 wavetables.