I always purchase extended manufacturer's warranty 100k,10y/0 ded. Here are my results:
2006 Honda Odyssey - no claims, total loss. warranty was $1500ish
2010
Infiniti G37, - 2 claims, $5000 (steering rack replacement, rear subframe replacement), warranty cost $1500ish
2012 Subaru Legacy CPO, 1 claim $300, warrant cost $1500ish
2018 Subaru outback, no claims yet. warranty cost $1600
2018 Subaru Crosstrek CPO, no claims yet, warranty $1600
2020 Subaru Accent, no claims, warranty cost $1700.
2020 3.3 G70, warranty cost $1900.
The only time I did not purchase a manufacturers warranty was a 1990 VW Corrado. The third-party warranty sold by the dealer was a major hassle, and then the warranty company went bankrupt. Total loss. It would have been useful for this car because the brakes totally failed at about 60k, and repair cost was over $3K (VW lost me on this, they were horrific, they could not figure out the problem and only solution was to complete replace the entire brake system). I declined and dumped the car for almost nothing, so loss was even greater.
Overall, I might be better off with no extended warranties, but 3 of the cars are for children striking out on their own, so they will not have to worry about unexpected repair expenses.
Also, extended warranties have huge markup. Subaru warranties were relatively easy to discount, because some dealers were selling warranties steeply discounted via email/phone. My local dealers were willing to match the online price, as soon as I mentioned buying it elsewhere. Some states do not allow this. I have heard that Subaru is cracking down on the practice.
I do not know if Genesis dealers are willing to bargain only on the warranty, but it may be worth a try.