I have a custom built comp. prior to that i bought prebuilt because not everyone knows how to assemble and just wants to get warranty coverage. Not many DIY PC businesses offer that without charge for labour. I know DELL does offer 3 years onsite (Part replacement / repair and no charge). That is one of the reason why people buy branded.
had a guy link one of the ibuypower pc from best buy and the only real varience would be picking brands you prefer as the difference was minimal and the only real money saving would be to buy those win 10 keys from game reseller sites
Or you want to keep gaming wherever you are. I went from SLI GTX 780Ti desktop to a laptop with a 1070 and better performance. RAID 0 PCIe SSD's. Overclockable CPU, and 120Hz display.