I always loved the reach weapon designs :s.

Just something about the chamfered edges and that no angle is too harsh makes the whole design seem much more tangible than any other incarnation of the weapons. Plus the fact that functionality WAS added visually. For example, the assault rifle. In Halo 1/odst it just looked like 3 chunks of metal slapped together and fastened with bolts. In reach not only was it split in to sections that made logical sense, but some sections were obviously interchangeable with other components that would be more useful to a not-spartan. Like the ammo counter could be switched with a sight. It also looks like a foregrip/ grenade launcher could be added if you removed the flashlight. This carries over to all the other weapons. I love it.