I have n56vz with i7 quad core 8gb 1600ddr3 ram and 650m. I would recommend the i7 version purely because it is a quad core, over the i5 3210 which is only dual core. 6gb would be enough to play battlefield. I will replace my 750gb 7200rpm hd with a 240gb intel 330 ssd which I already have, just been trying to figure out how to make recovery disks to restore win 8 pro onto the ssd. I would recommend you do the same.
Yeah, i7 is definitely over i5 but I would like to know whether it makes noticeable difference with BF 3