If battery life and working on the go is important to u, then I suggest not considering the laptops I and the rest here have mentioned, go with the xps or gigabyte aero 15. Much more costly, yes, but xps, aero all have at least 7-7.5 hours of battery life. Macbook pros/airs iirc can go for as long as 8-9 hours BUT, ofc, drawback is shitty specs and NO dedicated GPU, no gaming, you might as well get an ultrabook.
Gaming laptops, on the other hand like the much cheaper G3, Lenovo Y530, Apex-15, ALL aftershock gaming laptops in general have crap battery life. You'll need to bring along a horrendously bulky charger if you're gonna be on the move constantly.
Apex-15 currently has the worse: only 2-2.5 hours. The rest average about 3.5hours, my Prime 15 can pull a max of 3.5 hours.
If you're just choosing the XPS 15 for the weight, the Apex-15 weighs about the same and is actually thinner than the XPS, altho build quality is inferior to the XPS. After using a slim-and-light laptop(Prime 15) for a long while now, the difference in weight and looks honestly dont mean much when i look back on how much more I could've saved had I gone with a normal sized gaming laptop.