"The Trial" is also an excellent one as it shows the lengths Angel will go to protect Darla, despite her history.
"Epiphany" is also good as it shows a humble Angel how must deal with his mistakes and beg forgiveness from his friends.
The season finale is also good because there is the introduction of a demon dimension as well as Fred –a human slave/nuclear physicist.
Overall season two works well, it deals with Angel's demons as well developing the characters further. Cordelia in particular becomes a warrior and a champion losing much of vanity and vapid exterior to fight against the forces of darkness