Comparison Between Laptops!

I want to purchase laptop,configuration as follows:

3rd Gen.i7/8GB Ram/1TB HDD/2GB Graphics:-

I saw three brands:

1) Dell Inspiron 15R Special Edition(7520)

2) Asus K55VM-SX086D

3) Lenovo IdeaPad - Z580

Suggest me Best from it!

Thanks in Advanced.....!!!!!