Cubing
Dayan Guhong
This is a great speed cube although you may occasionally have popped pieces. It is not as fast as some other cubes, but it is very controllable and has very smooth turning. Corner-cutting on this cube is very good. I suggest this if it would be your first speed cube.
Dayan Zhanchi
This is a favorite for many speedcubers. It is known for its speed and almost uncontrollable nature. It comes with torpedoes, which prevent pops. There may be a few lock ups from overshooting, and also from the torpedoes. It has a nice "clacky" feel. I recommend this to more experienced cubers.
Moyu Weilong
This is Feliks Zemdegs' main cube. He currently holds the world record average time of 6.54 seconds. That just shows that this cube is a very good one.
What speed cube should I get?
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Moyu Sulong
This cube has that "clacky" feel that the Zhanchi does. It is fabulous straight out of the box, and requires no breaking in. It has torpedoes, so it doesn't pop, but it locks up instead. The corner cutting is okay,but still good. The Sulong is better than any other straight out of the box.
GQTimer