The Kia Optimas typically last around 100,000 miles before having any problems. The Lexus IS 250 is very reliable compared to Optimas. You have to realize that Lexus IS 250 is a luxury vehicle so you have to expect to pay more than a Toyota. For me, I will pick the Lexus in this situation. Most of the time I usually buy Toyotas for maintenance, longevity, and quality.

For longevity, quality, and a better overall owner experience go with the Lexus IS250.

Lexus no question.

Lexus, unless you want a new house in which case buy the Kia and park it in your garage and wait for it to blow up.

No contest, get the Lexus.

How long do you plan on keeping it? The Kia will likely start falling apart within another 50K miles. The Lexus will probably go another 200K miles.

A resounding NO to the Kia Optima, as it is a defective vehicle:

https://kiaenginesettlement.com/

2011–2018 and certain 2019 Kia Optima, 2012–2018 and certain 2019 Kia Sorento, and 2011–2018 and certain 2019 Kia Sportage vehicles suffer from a defect that can cause engine seizure, stalling, engine failure, and engine fire, that engine seizure or stalling can be dangerous if experienced, and that some owners and lessees have been improperly denied repairs under the vehicle’s warranty.

I could've sworn I watched a Scotty video not too long ago with this same question on one of his youtube videos, but can't find it to link to it. Lexus, no question about it. Even though the Lexus has more miles, it's a better built vehicle. 

Lexus all the way. While a Kia would be cheaper, it would not last as long and will fall apart sooner than you would want.

Get the Lexus if you want something reliable. You could get the KIA and wait for the wheels to fall off. Bottom line, get the Lexus its much better quality and engineering.

KIA as a temporary car.