What is your budget for the PC? Do you have any specific tasks or software you need to carry out on it?
What would you like the system to look like? Where will you put it? Would you like any peripherals?
SSD or super fast NVMe SSD drives? What capacity Hard Drive? How much RAM? Any preference on brand/manufacturer?
Do you need a graphics card? Do you need a configuration of more than one card? Tell us what you are using it for if you would like us to advise.
Do you need built in Wifi? Would you like a DVDRW drive?