Stormfang. If I wanted an assault vehicle I would use a Land Raider, having to hover to assault removes the benefits of being a flyer while retaining the downsides and the potential for your squad to explode with it. The Stormwolf is bad for the same reason trying to use a Stormraven as a dedicated assault vehicle is bad. You're just asking to have your expensive flyer explode, and putting a killy squad inside just makes it an even juicier target because it will take them with it. At least a Stormraven has skies of blood/fury/shadow to drop off a unit and still stay fairly safe.