CPU, PSU, GPU, coolers. Why should someone pick an i5 over an i3, or an i5 over AMD? Why go with this seasonic PSU over this rosewill? Why pick the MSI 970 over the Zotac 970? Why choose the nh-d15 over the h100i (aside from aesthetics)? All of the major components we suggest have been pitted against each other in the same games/usages by many reviewers(anandtech, linus, ncix, etc). Benchmarks offer and objective way to say "this part will give you more performance benefit over this" instead of "because I like it". The latter reasoning is completely acceptable, so long as someone says that's their justification. I prefer MSI GPUs, Samsung SSD, WD HDDs because of personal experience and is why I recommend them in my builds(over EVGA, crucial, Seagate). Are they objectively better in all situations? Maybe, maybe not. Are they what I've had a good experience with, stable, no issues? yes.

http://www.relaxedtech.com/reviews/noctua/nh-d15/8

Something like that gives you knowledge and numbers of what you're picking. H100i because you want silence? Hell no(its 33dba on max). H100i because you want more cooling performance over air? nope. H100i because you like aesthetics, sure, that's a reason I won't argue with! But so many people suggest water cooling because "its better" but benchmarks show its not(at least with stock fans) until you get into custom loops.

PSU's have also been tested and often times people pick platinum over bronze/gold thinking it's better. It's not, its just more efficient. A seasonic bronze will be better than say, a nonname platinum, it just may put out more heat. this isn't really a benchmark but it's a list of high quality psu based on tiers