This may sound cliche or be a response that most would roll their eyes at, but my favorite card is Jace, the Mind Sculptor. Playing Mythic Conscription during its heyday and then switching over to U/W CawBlade before and after Jace and Stoneforge Mystic was banned, I have fond memories of the card and still can't help but smile every time I cast it. Even though it's only legal in Commander and Legacy as widely supported formats, I'm looking forward to the day when I acquire enough revised dual lands to be able to bust out my playset of Jaces once again and give Legacy a legitimate shot.
So yeah, my favorite card is Jace, the Mind Sculptor.
EDIT: Woohoo, 1500th post in this contest, which means that my chances of winning will eventually be less than 1:100. Oh well, here's to sick rips off of Jace's Brainstorm!
So is Rancor.
I'm calling them canlands for two reasons. They are based off of Horizon CANopy, and since they draw you a card like a CANtrip does, CANland is the easy term to remember. Rolls off the tongue like shockland, fetchland, fastland, etc.
Stick this on a Dryad Arbor with Intruder Alarm out.