Looks like ESPN has ranked the top NFL helmets. Steelers and Colts are 1 and 2, according to them.
Apart from inexplicably putting the Dolphins in the top 10 and leaving off the Rams, who invented the helmet logo, for goodness sake, it's a pretty good list. And it inspired me to make my own. This list is below. This is harder than my previous NFL uniforms list because no NFL team has a truly bad helmet design at this point. Even the Bills, who I rank lowest because of their annoying multi-shade-of-blue thing, have pretty cool helmets. But once again, you'll see that I have a preference for the classic old-school look, as well as helmets of distinction (eg. Steelers' logo only on one side, the Eagles' wings, the Rams' horns). Heeere's my list:
5. Rams (they were better with blue and yellow, not blue and gold)
6. Chargers (would rank higher if they went to the old 60s helmets with the numbers on them)
12. Vikings (would rank higher if I didn't spend most of my childhood trying to figure out what the heck their logo was)
32. Bills (will jump in the rankings as soon as they get rid of the horrible 3-shades-of-blue thing they've currently got going)