I can speak to this a bit. We drive electric things a lot of the time so the gas cars are for fun….. Assuming we are talking manual sports sedans, the M3 and the 4V Blackwing are your only choices (save the 5V) and are as direct of competitors as you can find. I am in love with the last gen M2 Comp but I use all my cars to shuttle kids around between hockey rinks so I figured I would have to get the M3 and I ordered one.
I think the both cars can look great. I’ve got no problem with the gaping grill and the Blackwing (only with the carbon

) looks mean as hell. The more I read and watched while I waited for an Isle of Man green M3, the more I thought maybe the Blackwing would be better to drive so I found a purportedly imminently inbound black carbon/manual 4V in TX at msrp last spring and put a deposit down. That wait stretched out, too, though, and I found a mega-specced Sao Paulo M3 with all the carbon options and blue interior with just a couple thousand miles on it for a great deal. (Like I low-balled them and they shockingly said ok.) I thought this car is so wild, I’ll deal with the shifter not being as crisp….
I cancelled the BW order and drove the M3 back across the country and over the weeks that followed I realized I didn’t love it, despite the heads it turned. It was damn near silent, the shifting was….fine at best but inconsequential. Those two things I could fix with some work but the longer wheelbase made it nothing like the can’t-go-straight M2 I loved. It was too stable, too competent, too polished, too fast, too numb. Fit and finish and materials were leagues above the Cadillac although I didn’t care for the current iDrive or the bizarro vertical tach. Still, I loved almost everything about the car except driving it. It’s a really good car, extraordinarily capable but not a ton of fun with the mediocre manual. So before I spent another $10k+ on aftermarket bits, I traded it in for what I had bought it for. I’d put only 4000 miles on it. I cancelled my M3 order (that I had shifted to an AWD Comp) and bought a Stelvio Quadrifoglio which makes wicked noise and is very fun to shift (for an auto).
I recently added a Mini JCW because I was still dying for a manual. The transmission in that is very good, way better than its distant BMW cousin. Yet I can’t keep my eye off of the 4V Blackwing listings…. I only drove one once. It was a stripper and I hated the base seats but the stick and the clutch and the chassis have stayed with me…..they were excellent.