Unlike aircraft that become hangar queens after a relatively short period of time, the only GV that I see as a hangar queen is the 251 - you simply see M3s instead.
While the proportion of aircraft to armor is certainly skewed one way, no one is asking for 55 new GVs.
Realistically, 5-10 new GVs would probably shut everyone up for awhile, provided the were balanced.
Personally, I'd love to see a Jagdpanzer IV/L70, hell, give us an L48 and perk the L70. Low profile, Panzer IV chassis, 75mm high velocity weapon. 2 for 1 in terms of 3D modeling (especially since we already have a PzIV chassis)
M18 Hellcat - good speed, good weapon, excellent visibility from the turret (cuz its open top).
M10/M36 - make the M10 a non-perk, and perk the M36 - 2 for one in terms of 3-D modeling, etc.
Panther/Jagdpanther - mid-perk, excellent gun, good speed and maneuverability.
Fix the Tiger I - or at least adjust the perks on it.
Toss in something that will rule the battlefield - A Tiger II, JS-2, Pershing -give each an inherent weakness (Tiger II, mechanical or speed, for example), or perk the snot out of it.
Bring the little hills back and adjust some of the long-ass spawns that make us drive for 20 minutes. I feel that anything more than a 10 minute drive (direct line, with no resistence, between two spawn linked bases) is too much. I don't play the game to spend the majority of my time just driving to a point, especially when the chances of dying once you get there is pretty high.