For me, it's Byzantine. Though I have a minor in music, specializing in Renaissance polyphony which drew much of its inspiration from Gregorian chant (which i still love, when it's done correctly), it cannot compare to the variability and versatility of Byzantine chant. It can be austere and joyful, solemn yet playful. I love the poles that it presents.
As to comments as to Antiochians do it whatever way they want, this is true. For instance, every week we are given the notes for the service according to the Typicon. Many of the stichera for "Lord I have Cried" and the Aposticha that are not part of the Octoechos, but honor the saints or feast, are appointed to be chanted using special melodies. This is very often not done (I will confess my own shortcomings in this regard) and instead the chanters free chant almost everything. It needs to be corrected, but I'm new and I don't feel I'm the person who should be bringing this up!
On another thread, I remarked how difficult it was to get Byzantine chant settings for various parts of the Liturgy. Many of you were quite helpful in finding alternate sources rather than simply singing hte soprano line from the Cherubic Hymn of Arkangelsky or Bortniansky, etc solo. If anyone else has other suggestions or sources beyond the Divine Liturgies Project, I'd be most grateful. I'm really disappointed that the Antiochian website is SO devoid of chants but favors the harmonized chants, most of which just don't sound right.