Wow, great topic idea! Here's my $0.02:
Best Performance:
1. Henry Czerny as Conrad - hands down. Every single person on this show has had to deal with clunky dialogue, ridiculous plotlines, and inconsistent characterization, but he always managed to elevate the material he was given.
2. Gabriel Mann as Nolan - Definitely the heart of the show.
3. Emily Van Camp as Amanda/Emily - Because ultimately if she hadn't gotten me to care about her story, I would have bailed on this show long ago.
Honorable mention: Joshua Bowman as Daniel, Amber Valletta as Lydia, Margarita Levieva as Emily/Amanda, Max Martini as Frank
Worst Performance:
1. & 2. James Tupper and Jennifer Jason Leigh as Amanda's parents. Don't do drugs, kids, or you may end up with the affect and personality of these folks.
3. Dilshad Vadsaria as Padma - She was saddled with a dramatic, emotional story, and I didn't buy any of it.
Dishonorable Mention: Connor Paolo as Declan, Christa B. Allen as Charlotte, Justin Hartley as Patrick