GSkill got very popular as for quite a while they were the lowest price. However, w/ all the big boys matching their prices last couple of years, the attraction for me at least is gone. Most of my returns over the years have been Gskills, so w/o the price advantage, they held no attraction. I have also found they "don't play well with others". When upgrading older boxes, I have has more compatibility issues mixing different brands of same specs w/ the GSkills
For budget RAM, of late I mostly buy these Corsairs DDR3-1600 CAS 9 for $75
http://www.newegg.com/Product/Product.aspx?Item=N82E16820145324
For high performance, of late I generally buy these CAS 7 Mushkins for $130
http://www.newegg.com/Product/Product.aspx?Item=N82E16820226178
Don't bother w/ higher performance rAm when your CPU or GFX card will be the bottleneck as the faster RAM will only help when that's not the case.
I have not had anything out of the ordinary with respect Crucial or Kingston. I returned my very 1st Mushkin module (wouldn't pass memtest) about 3 months ago....with 2-3 builds a month of late and going back almost 20 years.
Higher speed is better but the cost premium can get prohibitive at the upper end.
Lower CAS is better but only comes into play if bottleneck isn't at CPU or GFX card.
http://www.anandtech.com/show/2792/12
22.3 % (SLI) increase in minimum frame rates w/ C6 instead of C8 in Far Cry 2
18% (single card) / 5% (SLI) increase in minimum frame rates w/ C6 instead of C8 in Dawn of War
15% (single card) / 5% (SLI) increase in minimum frame rates w/ C6 instead of C8 in World in Conflict