The Team Arena Paddles are outstanding for training, many of our swimmers use the Team Arena Paddles and have had great success and have little or none shoulder problems.
Mel
YMCA Indy SwimFit
For me, I don't use paddles to pull harder. I use them to "test" my stroke. If my stroke is off, the paddles get "stuck" in the water. (I catch the surface or they pull opposite the direction my hand is supposed to be going.) It tells me where I'm not being efficient with my stroke.
Is there a big difference?? Do color, size, and cost matter to you?
And unless, you are a high-end swimmer working specific fine tuning, almost all hand paddles will accomplish the same basic functions. In fact you can build you own at home with plastic and surgical tubing. For the most part, the primary difference is in the additional surface area by which they increase your total pulling surface.