Sanny -- In #14 and #15, I like the small cut you put into the "x", as well as the contoured arrow at the end. However, the box on the left feels too boxy and busy. Instead, perhaps you can use some sort of gradient 3D effect to achieve a more minimalist/pure feel. Here are some examples:
http://www.1stwebdesigner.com/inspiration/30-logo-designs-using-gradient-3d-effects-inspirationpart-3/Our old logo (
http://axeleragroup.com) may provide a good basis to build upon.