If High-end Gaming is your priority, then don't fill it with 4 sticks. Games usually don't use more than 3GB (as almost all are 32-bit), therefore it would be nonsense.
Also, having 4 sticks causes much more problems of instability (when bought separate, even worse), and tend to get worse timings and/or clock speed.
Then again, 8 GB should be your top if you want TOP PERFORMANCE.
G-Skill is nowadays gamers first choice (usually). Anyhow, if you buy top of the top G-Skill RAM or top of the top Corsair's, difference in fps will be no bigger than 2% (and most probably, close to 0%). Don't go nuts about it, G-Skill are usually very reliable, go for them as almost everyone does :P .
Hope it helps.