Edit: I may hv misread/misunderstood the thread title-original answer follows;
Reversed for me; I associate the acts first, then only their company-Like this: starting from early 2000s(not sure exactly when -till early/mid(?) 2010s)
BoA, SNSD, Super Junior(im kinda cheating here cos I include 2 female acts n also I only knew abt SuJu teally just by osmosis, never learnt much abt them until ard 2018 when I really heavily got into kpop, as far as I remember)- SM Entertainment
Rain, Wonder Girls-JYP
PSY, 2NE1- YGE
(I'm only listing the first/earliest acts from the Big 3 that I knew of in the 2000s/2010s but I dint know/pay attention to their companies then, (I'm not sure I knew/paid attention to the companies until I read abt SNSD Jessica ~out of SNSD in 2014 or maybe later in 2017, when 3 members left SM but not SNSD).
Edit again: my revised answer to thread title, after rethought;
SM-Suju, SNSD
JYP-Twice, no male artists come to mind unless my original answer above
YG-Big Bang, 2NE1/BlackPink (I can't choose from the two.)