I test drove both before buying the Lexus, I also had an E90 before this, for me it was just the quality of the materials used.When you guys say the interiors of the Lexus' are better than BMW's, what exactly do you mean? Is it the quality?
To be honest, as much as their engines are reliable, I've never managed to come to terms with the interior styling of the Lexus models, even on something like the LC500.
The F30 BMW's interior is better but it is not made better by a LOOOOONG way if that makes sense. I prefer BMW iDrive, I prefer BMW's layout far more than the Lexus, but I couldn't get over the fact the F30 I was looking at (coincidentally the cheapest with the mileage I was after) was still 90k more than the Lexus.
The F30 felt cheap inside, look the seats and steering wheel were amazing, but the rest to me just felt like Ford or Hyundai made it. I am not sure if the F10 uses the same materials but the F30 I tested was VERY disappointing. It had less than 90k km on it and several of the buttons were frayed through so you could see the ugly white plastic underneath.
Not to mention the cheap plastic they used on the dash itself, for a car that cost probably just under 600k in 2014 I was expecting more. If the buttons were already fraying through at under 90k, what would the car look like at 200k?
On the other hand my E90 (pics below taken at around 240k km) the interior was faultless, it looked as if it had 60k km on it other than the common door handle goo issue.


Now in comparison I simply looked for 335i's on Webuycars website, check out this advert https://www.webuycars.co.za/buy-a-car/C44DF1732 I have uploaded a picture below, this car has 172000km on, not a little but not a terrible lot by todays standards and look at the wear on the start, steering wheel on the right, and climate control buttons, yes I am being petty but one would expect more from a car that cost what this cost new:

I would say this statement: If you are planning to keep a luxury car for 7-10 years and want quality and reliability, buy a Lexus, if you plan to upgrade every 3-5 years then definitely go BMW, you then won't feel the lack of quality in the used market and from a driving perspective they are better.
That being said if I had R1m to spend on a new car would I buy a 4th Gen 2021 Lexus IS350 (if they ever bring them here) or a BMW 340i? I would choose the 340i every time. However I/we all have to work within our own financial limitations and for me I needed the most reliability and quality for the money I had saved, the Lexus isn't as exciting as a BMW but I am willing to sacrifice that for now. The E46's and E90's gave me the vibe that you could take them to 250-300k km without falling apart, the F30 doesn't but this is only my opinion.
Hope this helps!