It depends on you. Review on Branded Vs. Assembled Computers

If you are a general user who uses the pc for multimedia, internet browsing and a little bit of software use, you can get a pre assembled computer/branded. because it is mage for general use and not for some specific use and heavy use like gaming, video editing, software developing, etc. if you want to do a specific task on your pc like gaming, it would be rather be preferable to assemble one and get a good graphics card, if you want to do video editing or software developing you need to get a good processor, and if you want to do heavy work on server you must get a good motherboard having accessories like high end LAN and many ram slots. there are many components in a pc affecting many task performance, depending on your personal use you should get a favorable component. if you want a high end gaming pre assembled computer it would be more expensive than assembling one.