Deciding it was time to finally archive my old faithful (heavy, heavy duty, poorly fitting) Joe Brown helmet after a couple decades, this weekend at VAR I checked out and tried on every helmet IMO stocks and even some that cavers were wearing. Nearly everyone who came into IMO's tent while I was modeling and inspecting helmets gave me advice, promoted one make or another, and pointed out deficiencies in others.
I found that the style of chin strap-suspension (or non-suspension) set up and the fit were the two things that really differentiated the helmets. Check out the suspension-chinstrap style, features, and workmanship.
The fit and the comfort of the fit (depending on where the helmet set on my head, the finish on the headband, and the style of the suspension) varied greatly between helmets, and what was comfortable on someone else's head wasn't on mine. Perhaps my head doesn't have an off-the-rack, normal shape.
But perhaps yours doesn't either!
Normally I'd say that color is the first factor in choosing anything. I really wanted that turquoise Edelrid Ultralight, and tried ever so hard to make it work, even thinking how I could modify the headband! And that black "Starship Troopers" helmet looked very cutting edge indeed.
However, wisdom overtook me, and I finally decided on the helmet that was the most comfortable; had a headband that touched my head all the way all around (some had gaps over a finger wide on either side between my head and the headband, even when the helmet was fitting snugly!); and that had the least amount of movement on my head when the chin strap was adjusted properly, as Hank advised.
So my advice, Caver 1402, is: Don't take our advice on helmets. Just take our advice of trying them all on, finding the correct fit, and not hesitating to spend money on a quality helmet -- your head is worth it.
(New owner of a red junior
size Edelrid Ultralight -- yet I sure don't have a small hat size! The helmet is the same sizeas the regular Ultralight, but the suspension has a different construction and ride. )