Should I buy Dell XPS 13 or XPS 15

Tauxi

Commendable
Aug 12, 2016
23
0
1,590
Dell outlet has 500$ off and 5% student discount. There are 2 configuration at same 882$ below:
Xps15, i5, 4k, 6 cell battery
Xps 13, i7, 2k screen, 4 cell battery

Which one should i buy, i only play Fifa 16-17, working with matlab and hope battery lasts for 6hrs.