It was Shattered and Asylum that finally managed to get me hooked on this show. Before that, I would try and watch, but it always seemed like I tuned in during one of those interminable Lana/Clark talks about how they couldn't be together or something.
Asylum is painful to watch. It's painful to watch Clark try and save someone he loves and fail, it's painful to watch Lex be tortured by Lionel and told that it's for his own good, it's horribly painful to watch Lex try and make a run for it in the teaser, it's painful to watch the final scene between Clark and Lex. It's all just painful. In a good way. I love the fact that they had Clark being drained of his powers result in Lex being saved from the electroshock therapy and then Clark getting his powers back immediately lead into Lex getting the electroshocks. I have to say though, it really bugs me that the final shot of the episode is not on Clark walking away from his friends. That kind of thing makes me feel like they don't understand what it is that is powerful about the show.
Rosetta was enjoyable because it had internal conflict for Clark about things that actually matter as opposed to his usual romantic angst. Plus, I always enjoy seeing Clark go against his parents wishes for a little bit. Plus, great guest star.