I have two favorites
1) The Kristen/Susan storyline. I loved it sooooooooo much, it was fun, interesting, edge of your seat story. When Kristen was "faking" her pregnancy it was awesome and Eileen Davidson playing the duo roles wasfantastic!!(She played other roles too) THese were the "good old days" but it's coming back! Just wait and see.
2) Carly being buried alive by Vivian. I was so into it that I would bring my TV outside so I could lay out in the sun and watch DOOL at the same time. Very interesting storyline.
Worst storylines are most of the Reilly years. I would miss days if not weeks worth of episodes, now I'm watching again daily, something I haven't done in years. I feel the new writer is doing a good job considering he has a huge mess to clean up because of Reilly. It's a huge transistional period and we must be patient because these changes are for the best and are not going to change overnight. In my opinion, it's on it's way back to the top. Imagine how good the show will be in 6 months to ayear. Best things come to those who wait and I've waited years as have many of us.