This answer will come as generic, but here it is: only you knows your needs and what setup is better for you. Both desktop and laptop are valid options and will give you lots of hours of gaming, but if the portability of a laptop is a bonus, then go for it.
Besides, the needs you have now may change by the time you upgrade so, don't overthink it.
Please excuse my bad English.
Currently gaming on a PC with an i5-4670k@stock (for now), 16Gb RAM 1600 MHz and a GTX 1070
Steam / Live / NNID : jonxiquet Add me if you want, but I'm a single player gamer.