The Hays 7x7 from YuXin is by for the best 7x7 to hit the market. This cube is built for speedcubing. It is the perfect size to turning quickly, the colours are very vibrant and the texture is feels great in your hands.
This is the magnetic version, magnetized from the factory. The magnets are not too strong, but there to help accuracy in turning quickly.
If you are serious about your 7x7 times, then this cube is for you.