Tanabe NF is very comfortable, almost like standard spring, only slightly more firm. I'm currently using it for my Mark X and I'm very happy with my choice, the most comfortable lowering sport springs I've ever tried so far. It's lowered by around 3cm, so it's just nice enough, and not too low.
Btw I've used Eibach as well before and the ride is more bumpy than the Tanabe NF.