Well really this depends on what you are meaning to do. Now I will NEVER
recommend the Emachine brand as it is just VERY cheap. I will tell you now as a prediction, if you buy a Emachine then either your Motherboard or PSU will die, or even both.
Well here are my choices and my standards:
Dell - For the normal, non-enthusiast, person. The Dell BIOS was not built for a tech person, but more like for a person who will never touch the BIOS in their computing life.
Asus - For better then normal user, I would recommend this for normal use. Great computer manufacturer and I love the Gigabyte brand that you put above.
Alienware - For the best of the best computers, these bad boys are built towards video editing, high level gaming, and water cooling. If your doing major graphics work like with a 8800 GTX Graphics Card. Not for cheap people
I hope this answered your question