ASC traps vs. REALTRAPS ????????

which is better for aborbtion quality in the low bass range, from 150 hz down to 20 hz.? realtraps are flat and alot of ASC stuff tends to be cylindrical. ??? the ASC traps seem really expensive, like up $1000 for one 20" trap!!!! are they worth the extra cost when the realtraps are like 200 each?

thanks