Our team is having this same debate currently, and spend a good 2 hours today talking about this and we are still very split. There are distinct advantages to both, elevator (forklift) type system is obviously much simpler to implement and control, but has less freedom of movement compared to a 2-jointer. The elevator system also (depending on how it is designed) most likely heavier, and placing a heavy elevator on the front of a robot can wreak havoc on how the robot drives. However an elevator system allows the manipulator to be simpler and would be far easier to program an effective autonomous program. So there are large advantages and large disadvantages, all you have to do is limit the disadvantages.
