Reunion era, in a heartbeat.
Too early for me to comment on The Book of Souls, but the two albums before it are the best that Iron Maiden has ever done. BNW and DOD have their ups and downs, but both are more up than down.
No disrespect to the classic era—Live After Death is my favorite live album by any band ever because of the material from TNOTB, POM and Powerslave. But 1) I prefer the reunion era, stylistically, by a mile, and 2) the reunion albums, particularly AMOLAD and TFF (and possibly TBOS), are more consistent than most of the classic albums.