Note that all those guys are "assemblers".....they all buy parts from various component manufacturers and assemble them into one box....you can do the same yourself. The best PC is one you build yourself cause you know how it was put together.
In most big brand PC's, you will get 2, 3 or 4 hi end components and then they always wanna sneak a low end part in there to hit a lower price pint than the other guy. Most of the time, you can upgrade your way outta this.
I dont like brand PCs, as JackNaylorPE they seems to be good, but they usually mess it up. Not mentioning often custom drivers and firmware causing problems.
They are good for office use, but i would not want it at home even with 50% discount.
Depends on budget mainly.Quickness of computer doesn't depend on the brand,but the hardware.If you are going for laptop,never choose Acer,because they are heating too much.Whole package is built wrong by Acer.For laptop,go for HP or Dell.For desktop,just check the prices and hardware[also software].However,building your own desktop is much cheaper and you can get all the parts that you like and can afford.For desktop/laptop,I suggest going for HP computers.My preference.