If you want a small project that will result in an inexpensive yet efficient smoker go with a UDS. If you want to start cooking immediately and don't want to deal with a new project I recommend WSM. I just built a UDS and am loving it. I've had it going on 1 1/4 bags of KBB for over 28 hours and still running. I have no idea how long this is going to go but it's a test and so far it's passing with flying colors.
FEC120, XL BGE, DigiQ DX2, UDS, Cimarron, Weber Jumbo Joe, Grill Grates, ThermoWorks RT600C