Loops are not cheap. Not to do them right. It's more than just throwing parts in them. There's lots of research involved especially if you have an end goal like I did with mine. I wanted small, dual 240mm and silent. It's more than lowest temps, loops are designed for that, sure low temps are possible but over sizing rads doesn't mean anything alone. The right blocks, the right pump, the right fans, the right rads. All have variables.
Personally, from my experience EK blocks are decent. I think their designs are more towards showcase than performance. So far Watercool Heatkiller has shown the best overall results. For cpu blocks Optimus for Ryzens is #1, the Raystorm Pro is right behind. For ddc pumps, EK. Not sure on D5's. Rads have too many variables to count, noise being a huge factor there as thicker rads take more rpms generally so it becomes a fine balance of expectations and compromises, and even then, most rads have a range of best efficiency so matching fans becomes more a necessity than an rgb show. Is it beneficial to go with 2x 45mm 240 rads or 1x 60mm 360 rad...
If you can't afford to spend 6 months planning, researching, testing, comparing, deciding on the build and all its various components then you'll not understand your loops limits. Loops are about temp maintenance more than temp maximums. I'd rather have a loop that varies from 50-60°C no matter the loads, than a loop that jumps around from 30-70°C depending on load.
My loop is so silent I was forced to buy a rgb mouse, just so the wife could tell if it was actually On. She shut the pc down half a dozen times and then call me saying it wasn't working, did she break it. I achieved my goal of super-silent. A $1200 air cooled build that cost just shy of $3000 to finish with a loop. And took a year to accomplish.