Life Orb is generally better for Pokemon that are deadly when then can switch moves. Sheer Force and Magic Guard Pokemon face no recoil with the benefits of Life Orb. Examples include Latios, Terrakion, and Conkeldurr. The recoil from Life Orb can add up, especially with the prevalence of Stealth Rock in battles, as well as potential Sand teams.
Choice Specs and Band are generally for those Pokemon that can basically nuke everything. It has a large power boost in comparison to Life Orb, but being locked into one move often means you have to switch.
Basically, Life Orb's recoil and Choiced Items forcing of switches are cons, and Life Orb's ability to switch moves and Choiced items power boost are the pros.