4 and 5
Honestly, Alienware is overrated because it's expensive.
Bandwagon: everything expensive is good
I like it due to it's great gaming experience.
iBuyPower is good because their designs are sometimes slick.
Defiantly Lenovo is my favourite, I bought a Y580 Laptop with a i7 quad core, 8GB RAM and a GeForce GTX 660m, some of its beautiful features are the most basic, example a fan dust remover, two clicks of a button saves you a whole laptop disassemble (It really does work !)
Oh btw, it cost me £1250 .......
Money buys good things.
Alienware is way overpriced !
And when it comes to Desktop building AMD FTW !
But on a serious note
Case : Origin
RAM : Corsair Vengeance
CPU : AMD
GPU : Sapphire
Dunno about rest it would get picked as it goes