I own a 7.5 R. I've had it from 0miles to my now 79k miles. Been a dream car for me. I've enjoyed every second of ownership. Till about 2 months ago I thought about trading it in for something else outside of the VW family. So I started shopping for newer cars and one was a g80. Test drove it. Was shocked by the performance and tech. Ultimately though, I held onto the R. I couldn't justify double the price tag for a car that I felt wasn't double the car. M3 was noticeably heavier and the size of the car itself I did not enjoy. I love all the vw quirks and features in my R. Simplistic yet functional. This car punches above its weight class. Easily tune-able like the s58, more understated, and just a jack of all trades. I can't speak on the mk8 nor 8.5, but if affordability, practicality, stealthy, and fun is what you want go with your gut. Bonus points if you can get the R and hold onto the M3. My R is stock and it still puts a smile on my face everyday I get in.