Well like, I thought that too. Played a good five hundred games strait and then decided to try some Reach.
Then I went back and holy crap Halo 3 is ugly. Like wow.
Reach armor, chunky Spartans aside, looks the best, IMO. A lot more detailed than H3 armor and the designs were varied without looking ugly and overly designed like Halo 4's armor.
One of the things I'd love to see change in the 343-verse is the horrible Spartan IV armor. Recruit model and some of the basic ones look okay (even though they could use more actual armor) but the rest make no sense from a functionality standpoint and look like they belong in a complete different franchise. Just awful awful stuff.