Which laptop should I go for(gaming)?

The difference between the two CPUs is basically the clockspeed.

The core i5 has a base clockspeed of 1.6GHz, but it can go up to 2.6GHz when necessary. The core i7 has a base clockspeed of 2.0GHz, but can go up to 3.1GHz.

The core i7 clockspeed is up to 19% greater than the core i5. However, that does not mean you will get 19% better performance in games. Most games are limited by the GPU, not the CPU so that extra 19% in CPU performance may translate to a 0% to 7% increase in game performance depending on how CPU intensive the game is. Most games are not very CPU intensive.