After having quite a complex headphone journey, I've settled on a pair of Fostex HD600, and they are more detailed and dynamic and more open sounding than the Hifiman 400(i?) I heard. I found the 400 a bit too smooth, tbh.
The Fostex are quite a bit more expensive though - I got mine for £270 used, iirc - I'd say if you can pick up the Hifiman 400 new for £180 or so they are a great buy. Although maybe you should give a listen to some Grados as well for a rather different presentation.