Can someone please help me out? Which of these is a better buy and why?http://www.bhphotovideo.com/c/product/1009862-REG/asus_d550ca_bh31_15_6_notebook_computer.html
http://www.bhphotovideo.com/c/product/1009861-REG/asus_d550ca_bh21_15_6_notebook_computer.html
http://www.bhphotovideo.com/c/product/1009861-REG/asus_d550ca_bh21_15_6_notebook_computer.html