The current storyline with the Joker and Barbara Gordon getting closer and closer to a showdown is really getting me excited for each new issue that comes out. I like all the characters in the book, especially Barbara/Oracle who has always been a favorite of mine. Right now, whenever I pick up a new issue, is the first thing that I read when I get home.
It's warped, it's twisted, it's darkly funny. The characters are great, unique, and just freakin' insane. The villain is one of the most creepy, disturbing evil bastards out there. It's my absolute favorite book right now. Great writing, love the art, love the whole plot.
The whole New Krypton saga is off to a great start but specifically "Action Comics" has been just amazing lately. Geoff Johns' Brainiac story was incredible. It's a great time to be reading Superman stories but especially if you're reading action comics.