This is my main rig at my house. I replaced my 8700k/1080ti build which I am using now at my parents and sharing with my nephew.
CPU- I went with the 9900k because I wanted the fastest main platform CPU available. Yes the 2700x and 8700k are way better values and probably meet my needs. I wanted the best and I didn't want to wait for Zen 2 next spring.
CPU Cooler - I chose the kraken because the block looks really cool. I manage the fans through the Mobo and really only use the CAM software to control my lights if I unplug it.
Motherboard – I chose Gigabyte because they seem to have the best VRMs. I also like the m2 covers and heat sinks and how it looks. Looking back the Aorus Pro would have been fine but I am happy with the board. It was able to push the CPU to 5ghz easily.
Ram: I bought these a while ago and have transfered them through some builds. I like that it is 2x16 if I ever decide to back to ITX.
GPU - It was the only RTX 2080ti that fit in the Define C. I really like the compact desktop. The temps are OK without cranking the power limiter. If I set the power limiter to + 130, the temps get into the 80s. I can overclock to probably 2050-2060 if I went under water. It settles at 1980 on air but I use the power limiter at 100% to keep fan noise down so it pretty much clocks at 1800-1900 for my usage.
Case - It has great cable management, a pretty tempered glass window and it is very compact. It fits nicely on my desk. I only wish it was a hair longer to fit a monster GPU like the Trio.
PSU - I had the EVGA PSU from another build. 750 watts is perfect for a single GPU build. I doubt parts will get more power hungry then a 9900k/2080ti.
Monitors - I bought the UW a couple of years ago. It is very nice @ 100hz. The monster GPU can really push it to the limits with some head room,
Fans- I had the GT and the Noctua as extras so figured to shove them in there. Overall my temps are really good unless I really overclock the GPU.