I had a gc/agx set up on my car for a while which was decent for the price. I have k sports now, but havent driven my car with them in yet. I have driven my friends miata and his mirage with k sports many times and liked how both of his cars drove, thats why i bought the k sports.
I dont have much experience with megans from a street aplication, but for drifting they work great. I think 3 out of 4 of my friends that have purpose built drift 240sx's have megans, one of the 3 had silkroads and switched to megans, and he likes the megans. I have not heard of anyone around here with them on a b13 or b14, so i cant speak for those. Any suspension can be considered junk if the spring rates and dampers arent matched correctly.