Twilight showed what was at stake, had a great teaser, made the Xindi more chilling, had great space battles and lovely Archer/T'Pol moments.
Azati Prime was the beginning of the end. After some aimless wandering we finally start picking up steam. We get some fresh ideas with a waterworld, the ominous sight of the Xindi weapon in its cradle, we see the ENT-J and the 26th century where Daniels finallys puts it altogether for Archer, some mystery surrounding T'Pol's bizarre outbursts that pave the way for her arc of the season, nice interplay among the Xindi, a devastating battle with outstanding visuals.
And The Council is where the arc was no better realized as we begin the First Act of what was essentially a three-act tv film. More interesting visuals such as the sight of the Avian stronghold, the ominous launch of the weapon from the desert floor swarmed by Insectoid ships, the interior of the sphere; Degra's surprising and sad death; Hoshi being pulled into the mix in a critical way with her abduction; all the wonderful Degra/Archer and Degra/Trip scenes.