Okay...so we can all agree to disagree. But as one who has built two magazine BMW project cars, and know the marketing and technical folks at Bilstein and Konis, I'll just say that the Koni's are more liveable on the street at slower, urban speeds, over rough surfaces.
If you drove two identical e30s, back to back, one with Billy sports, the other with Koni's -- you could, as they say, feel the difference.
For another opinion, check out
http://www.bimmerhaus.com in Colorado. Owner Bob Tunnell has won 10 national SCCA autocross titles in e30s and e36s -- all on Konis. He's forever removing Billys and replacing them with Koni's for customers.
Both are excellent shocks, don't get me wrong. But for day-to-day driving, the Koni's are more supple around town. It's a fact. You might prefer Bilsteins and think they are okay for YOU, but don't tell me the ride is as comfortable as Bilsteins. They are not.
Cheers, Gary