I personally prefer Lemuria to Sirius B (they were released at the same time); Typhon, Lemuria and An Arrow from the Sun are the better songs, with only Son of the Sun standing out from Sirius B. For that more symphonyic non-power metalish stuff, I personally think Vovin offers far better songs than both Lemuria and Sirius B. Vovin to me is the trademark Therion sound, with basically every other album being different (more or less symphonic, more or less power metalish, more or less experimental) but having at least one track being Vovin'ish (in the case of Deggial, Sirius B and Lemuria - quite a few, Gothic Kabbalah - The Wand of Abaris, Alduruna Rediviva, and Sitra Ahra - Kings of Edom, 2012, After the Inquisition).
I like pretty much their entire discography. Not really a favorite band of mine, but one I can easily return to and listen through a few albums.