Seekers Series - It's an interesting series about a group of bears trying to save the wild. A tree-hugging series with a lackluster ending in my opinion, but still a good read.
A Series of Unfortunate Events - A whimsical (not so) little tale with despair and woe around every corner. A really good series with a dark, yet amusing charm to it.
1984 - The only school required book that I actually enjoyed reading. An interesting story about an incredibly overbearing government that is actually genius when you stop to think about it.
Great Gatsby - The only school assigned book I never finished. I couldn't force myself to read it. I found the book to be boring, dry, and slow. The movie was better, but not by much.
Animal Farm - I literally threw this book in the garbage and left it there as I layed on my bed in shock at how horrid this book was. Unfortunately, it was the school's so I had to take it out of the garbage eventually. I respect it on a historical level, but as a story, it sucks. Nothing happy happens past page twenty, and you're sent down a path of torture as you watch your favorite characters get picked off one after another. Probably the reaction the author was hoping for, but that doesn't mean I like it.
Sorry, I know you said list three for each, but I couldn't think of a third choice for worst book. I'm pretty picky about what I read, so there aren't too many books I don't like.