I have a Arai Vector, Shoei RF1000, Shark RSR2, and a Shark RSX. Previously have used HJC, and Scoripion EXO400 which both sucked, fitment and weight wise.
Arai is a nice helmet but they are one of the loudest helmets I own, it moves a lot of air but damn you better have some ear plugs. it also has a tendency to fog in colder weather or rain.
Shoe RF1000 is a great all rounder, it's not too noisy, moves a decent amount of air fits great and good balance of aerodynamics and weight. The perks of the Shoei is the helmet skirtings are short so if you don't exactly have a giraffe neck as this helmet gives you a free range of motion without it dragging on your jacket collar like some helmets. One example is in a agressive sport bike position the sometimes the jacket collar has a tendency to push your helmet forward which bugs me, this has not been a issue with this helmet. Like the Arai this one is also prone to fogging on cold or wet days.
Shark RSR2 and my Shark RSX IMO this has got to be the best winter helmet for a couple different reasons, it has the best noise insulation, not too much air moving around inside once vents are closed (good in cold temps), will not fog no matter how hard you breath inside with visor closed. Extremely comfy and lightweight, good aero balance at high speeds, fat 3mm visors. The drawbacks is it's not as friendly in the summer as it doesn't move as much air as the Arai or shoei, the biggest complaint is the smallish eye port which IMO slightly hinders the field of view a little. The Shark RSX i have is pretty much the same as the RSR2 in terms of comfort and feature but it's slightly more quieter due to less aggressive air venting. In fact the first time I wore it it was so quiet inside the helmet it almost felt like i was driving in a car, it was that good.