Nuh-uh, you did *not* just diss DBZ BT3! DBZ BT3 is awesome.

For me, in terms of life-suckingly addicting it would Animal Crossing and Elder Scrolls: Oblivion. Both of them I played obsessively for incredible amounts of time until I just suddenly stopped (out of necessity, not boredom). I have never touched either game since for fear of relapse.