IMO Mugen visors are aggressive and only looks good if you have other aggressive mods. You can get authentic Mugen Visors from a company called JHPusa and they are located in 626 (socal) for about $200.
OEM does indeed look a lot more smooth, and flows with the car even if it is stock. If you can catch them on sale they will be about $100, roughly the same cost as Mugen reps. Regarding the mugen style reps, k24 is selling, the contour lines does not match up to the authentic mugens, which is all I wanted to point out.