I was on Atkins and switched.
I did so much better when I switched to the Beach the first time around then on Atkins, made it all the way to goal and slacked off after some surgeries and let myself go again.
Now that I have started South Beach again for the second time, I already know what I am allowed to have and what not. Atkins just sort of got too boring for me with all the meat. Too limited on the Vegetables and Fruits and Dairy that I like to eat.
But you have to find out what works best for yourself. There are a lot of People on each plan that swear by it and had success.
Good luck in which ever way you decide to go.