Not personally a fan of 7 Wonders, while I enjoy drafting as a mechanic I don't feel like it has enough heft to make an entire game out of it.
I LOVE 7 Wonders duel! The gameplay and decision trees get really interesting, and especially playing against the same opponent repeatedly whole metas and strategies develop and get beat and repeat. Never tried the xpacs, as I feel the base game is so tight and interesting and I worry about adding extra bloat into such a lean system