Welcome, Mark! Boston butt was my first smoke in the #1 a year ago, and I've recommended it ever since! The nice, long smoke serves as a good break-in for your smoker, and shows you how it performs when it settles in for the long haul. Plus, the Boston butt (bone it) is hard to mess up!
I see Gregg has caught onto this, too!
Let us know if you have any questions - we're here to help!
Whatever you choose will be good!