Water cooling is as much of a hobby as anything else, picking the components and maintaining the system is part of the "fun".
Unfortunately, "fun" can give way to exasperating fairly quickly for the novice builder, so best they understand the pro's and con's. As an example, it never ceases to amaze me the number of watercooler builds I have to take apart because someone overlooked something elementary - wrong size fitting, hose bound up on compression fitting (use a dab of silicone grease), and forgetting to flush>reverse flush>fill/stand (with mild acidic solution like diluted white vinegar) a radiator (then repeat and rinse with whatever you're filling the loop with)to remove flux residue etc, etc.
Generally, knowing what you want to achieve and actually getting the desired result at the first time of asking takes a build or two- otherwise it comes down to trial and error and buying a lot of stuff you probably won't/don't need. As an example, a clean build uses the minimum amount of tubing running through the fewest bends (flow through angles introduces inertia), but most chassis' are designed to have 360/420/480 radiator ports towards the rear of the case -hence rear grommet profusion. Follow this layout and you have a return hose draped across the motherboard and over the top of a graphics card, or a long loop that snakes around interior til it meets the pump and res -usually towards the front of the chassis. No good for aesthetics, no good for cooling. Once you've done a few builds it maybe isn't a problem- you see whats achieveable, and you see what can be achievable at the same time.
My builds at the moment centre around the NZXT Switch 810. Good chassis, but has a couple of flaws in the design concerning watercooling. To mount the rad with barbs at the front requires either use of extender and dual/triple rotary fittings (resulting in very tight 90 flow change, or creative use of a hole saw (+ auto grommets) to enable a pass through:
Likewise, there isn't much in the way of options for a floor mounted pump. The Switch 810 seems set up for a bay mounted reservoir/pump (too noisy, a pig to bleed and maintain). The floor of the chassis has an inconvenient fan cutout where the logical pump placement would be. A quick custom cruciform plexi baseplate with the pump/res footprint superimposed alleviates the problem -note: The combined tank res and pump is much quieter than the hi-flow POM/Delrin tops available, has the same flow rate, and doesn't block airflow as a pump+multi option reservoir would:
So your whole loop becomes basically an isoceles triangle- from top front >bottom front>CPU (+ GPU if req'd) socket. After numerous builds this arrangement seemed rather obvious- I doubt that it would seem so obvious (or painless) if it were my first watercooled build. I hope it gives our OP some enthusiasm for the process. Good luck with whatever choice of cooling you make.