first of all there is no need of 8 as 8.1 is the more "upgraded" version of 8,Talking about what's best for laptop gaming.. Windows 8.1 may not please you as for UI "if you're MetroPhobic" but IT DOES certainly feel more Lightweight than 7 especially in boot times considering MS's tweaks to the Kernel and considering that you're on a laptop
😛 so ofcourse you need faster booting OTHER THAN THAT Windows 7 is more "OldSchool" one and has the old aged "Desktop" version of Vista and XP..so in the end your choice Plus don't forget that with Windows 8.1 you will get all the latest incoming updates which are certainly promising