I love the latter half of season 2. The Gambler, Triple Takeover, Starscream's Brigade, Revenge of Bruticus, Trans Europe Express and both parts of The Key to Vector Sigma are my favourites.

That being said the day I picked up the first part of season 3 I had a really horrible day at work. My boss was being a real tool (seems to happen alot). Anyway when I got home (my wife was working late) I cooked myself a couple of hamburgers (I love my own hamburgers) and sat down and watched five faces of darkness. It was a really nice evening at the end of a day I'd rather forget. Since then (although it's not the best episode/s) I still enjoy watching five faces of darkness if I'm sick or feeling down.