I second Tipperary, I just forget I'm wearing it and it looks sleek, no mushroom-head look.
I bought the Ovation Deluxe-schooler for my niece. I was impressed with how light, cute and comfortable it is. I just tried it on, so I really don't know how it would be riding/running for hours. I think the liner is washable, which is a plus.
Whatever fits your shape head the best. Go to a tack store that carries many brands and try on several to see what shape works best for you.
I loved my old Tipperary Sportage, but it was 6 years old and time to replace, so I got a new one. Unfortunately, the slightly redesigned newer style is not the same shape and gave me headaches. So now I have an Ovation Protege, which looks very similar to a Tipperary.