I've read Looking for Alaska and An Abundance of Katherines. I like An Abundance of Katherines a lot more. Call me strange, but the parts I liked best were the bits when the characters were used to reflect on life and its intricacies.
I have read Paper Towns, An Abundance of Katherines, and Looking for Alaska... The first one I read was Looking for Alaska and it is one of my favorite books, ever! I love how he made it a mystery, Why did Alaska really want to die? What were her real reasons for doing all the things she did? What really were her Last Words? A lot of this book was left up to imagination. I love Alaska. I love the Idea of cliques in that book, and I love that Pudge is kind of like and exception to these cliques. I also love the whole concept of Before and After. Looking for Alaska is Incredible, Paper Towns is interesting, and An Abundance of Katherines is sweet, in my opinion. But Looking for Alaska is my favorite. :)