The low end on Hive definitely sounds better. I find the Sylenth low end rather weak sounding. The hi end, I think I prefer Sylenth. Of the two, I would pick Hive because it's ongoing creative development. For example, it has just had the wavetables added, including user wavetable import. It also now has the Uhm scripts, which have a lovely and unique kind of quality. It also has the new u-he preset browser, plus some excellent new modulation options.
So for no additional upgrade cost, Hive now has a vast landscape of new sound possibilities that Sylenth cannot replicate. So suddenly, Hive is much more interesting!
