haha yeah, there are a lot of poeple that think that a fat neck is bad. mostly a neck is ment to fit your hand but they do also matter with speed and stuff. Jackson, usually makes very thin necks, which are great for sliding and stuff. BC Rich, in my opinoin makes the best neck shape. They are nice on my hands and are fast but you still have some wood under your hands. making it feel more stable.
for metal, id reccomend a jackson, any model, or a bcrich, something classic like a mockingbird or a bich. i myself got a mockingbird and after moving the strap button to the neckplate, because it has a serioussss balence issue, along with the kelly... and i think im just rambing by now so ill stop!