A mini-ITX build in a Streamcom DA2 case. PC will be used for mostly gaming. I used some parts from my previous machine (the video card). I went for a budget CPU with the Ryzen 3, however AMD reports plans to keep the AM4 socket for several years so I will replace the CPU with a fast 7 nm process chip in a few years. The place where I really invested was the 1 TB NVMe drive and I think it was worth it; it actually installs on the back of the motherboard (see pictures of the backside of the mobo in the case).
The Streamcom DA2 case is really clean and slick. It was relatively easy to work in and everything just fit even two extra fans (a 91 mm and a 120 mm fan, see pictures). The trickiest part was fitting in the 120 mm radiator & fan on the EVGA hybrid card. I do not think you could put in a 3.5" drive and a radiator in this case simultaneously. I threw in an old 2.5" SSD into this build. Hard drives mount just in front of the SFX PSU in this case so it sits very close behind the GPU radiator's fan: it may be restricting airflow. Cable management was tricky and if I really wanted to improve things I would perhaps order some custom shorty power cables now that I know exactly how everything fits. Space is tight but with planning it all works.
Update: A few months ago I put in a new CPU: AMD RYZEN 7 3700X 8-Core 3.6 GHz. It is great.