The T-grip is pretty much the opposite. It gives you a firm grip which is excellent in whitewater where you want total control of the paddle.
The third one, the Northwoods grip which is wide and long, allows you to either have the hand on top as with the T- and pear-grips or hold the hand in the same angle as your lower hand, making it possible to adjust the "shaft length" whenever you want. For the paddle maker the northwoods grip is also a great way to balance a paddle as it adds a lot of material on the grip side.
Historically it was quite comon with gripless paddles too. These were mostly used in big canoes powered by many people. Where only the stern and bow paddler needed the ability to steer. Nowdays I don't see anyone using that kind of paddles. But if you do know any please let me know!