I Wouldn't buy one that's tight around the forehead, you'll get headaches & it doesn't give much there. But also don't buy one that's obviously loose in that area too. Do the helmet strap up & try to roll it forward off of your head.
Try a few manufacturers & models to see which you find a good fit. Arai used to do models for different shaped heads, no idea if that's still the case?
Cheek pads do give a little, so snug there is good. Most decent manufacturers offer different thickness cheek pads if it's too loose.
Obviously a heavy helmet is less comfortable than a lighter one, just try loads until you find one you find really comfortable.