I have an Arai RX-Q and I love it. It is very easy to change the visors and is well vented. I get headaches if I get too hot, but I have been able to ride year round with my RX-Q and not have a headache in the heat.
I have a couple of friends who have Shoei's and they like them as well. I can't speak about the ventilation or anything though.
Personally, I recommend you go and try on some helmets and see what fits your head best. Wear it around the store for half an hour and see if any pain develops. One might just fit better than the other. Helmet manufactures use different head shapes so one brand that fits me well may not necessarily fit you well.