Buying new - barebones vs. pre-built?

Hi, I’m getting an hx99g for gaming in my living room. Right now I can get the pre-built 64GB/1TB on amazon for 799. Or, I can order the barebones from minisforum for 599, and buy 64GB of gskill ram for $150 and a 1TB HD for $80 and windows license for $25.

They end up being almost the same price: 799 vs 860. I prefer ordering from amazon and having it assembled for me. But I think the separately-purchased RAM and HD would have better performance, right? Is it worth spending a bit more and going through the hassle of assembly in order to have higher quality components?