Since you're new, you can be forgiven making this topic once. This has already been discussed in depth many, many, FAR too many times.
Short answer: Probably the F-II, A-V or Guhong.
Long answer: It's completely up to each cuber to decide for themselves what the best one is. You have to try them all out and see which happens to mesh with your own style.
I'd start with the three I listed above, because they are the most popular, but you should always try to expose yourself to as many different cubes as you can to make the decision for yourself.