I don't know what I'm doing wrong, but I can't tell what CPU is in the MT you linked to. The "Specs" link lists several. Not that I care. You want complete control of the build, from case to card reader, and the quality of the components is only part of the picture.
Your analysis will be based on the intended purpose of the machine. When someone posts a request for an appraisal of a gaming build in here, the first thing I look at is the graphics card. If they want to do heavy rendering, I look at the CPU. If they want a desktop for Mom, it's the price.
This computer building hobby will take you as deep into Techworld as you care to go. You have to learn all you can about every aspect of computers and make decisions for yourself based on what you've learned. You will make mistakes; you will spend too much and get the wrong stuff and get useless stuff you have to return. It's about fun and knowledge and craftsmanship and fun and pride and aesthetics and power and fun. Mostly fun.