On my 1st R34 GT-R (non V-Spec), I had Tanabe springs installed over existing coilovers.
They were a progressive spring and the ride was more even with a return damping effect that was hard to unsettle. I loved it!
On my 2nd R34 GT-R (V-Spec II), the OEM coilovers were similar to the above setup, and ride was comparable, but the ride was higher.
On my current R34 GT-R (N1), the OEM coilovers were harsh at slow speed on suburban roads.
I wanted more balance, and thus I now have S-Tune Nismo. More oriented towards track as well as road.
All in all, I cannot fault the Tanabe springs. I've been in a Honda with Tanabe coilovers and the ride was impeccable.
BCs I have not had I'm afraid to compare with.