First, choose whatever fits your head best. I thought my Shoei RF900 fit pretty well, but now I have an Arai Quantum, and my head shape is best in an Arai. Plus, the Arai is very plush and holds that plushness, unlike my Shoei, which feels rather rock-like inside after three years of daily use (versus the one year of use with my Arai).
The one caveat I have against Arai is that the helmet is damn loud, even with plugs. It actually squeezes my ears, so the plugs will wiggle loose (and they're custom plugs). My Shoei is as quiet as a "bee-loud glade," to quote W.B. Yeats. The Arai is Hurricane Isabella at regular speeds (it's the side panels that do it, but there's also a lot of turbulence underneath the helmet, which I can block out with my hand or a scarf).
I still love the noisy bastard, though.