Cbe, the Avantis go lower, and give more of a sense of volume/weight to instruments -- also closer, IMO, to natural sound when properly set up. So, better. Also more expensive. The new Avantis are easier to drive well than previous models, i.e., to get the best out of them without "euphonic" brightness.
The Virgo is a well balanced speaker, however, and a system that rocks with it will not necessarily do so with the bigger (+more demanding) Avantis. Considerations: amplification (speed & current), room-size.. to name a few.
This being said, I auditioned the NEW Avantis at the local dealer, not at home; amplification was S-Line that matches very well, as Gregg notes above.
Conclusion: if U read this, pls remember my limited exposure to this gear. It could very well boost the magic in your system... but then again, the Virgo is a great speaker IMO.
Good luck!