AH-1W Cobra - CAS (Close Air Support) and FAC-A (Forward Air Control - Airborne)
UH-1N Huey - FAC-A, C & C (Command and Control), Utility, some CAS
CH-46E - Assault support (generally a stick of 12 although we carried 16 in Somolia), cargo
CH-53E - Heavy Lift is the primary mission but the Big-E is a very versatile machine and carries out a range of missions include long range insertions, special operations, and troop transport (I believe they are limited for political reasons to carrying only 36 Marines). However, the 53E has such a tremendous reserve of power that it can carry 36 almost regardless of the range, temperature or altitude unlike the other helos above.
The 53D just sits in Hawaii....
Size wise: the 46's max gross weight is 24,300 lbs, the 53D is somewhere around 53,000 lbs, and the the 53E is around 73,000 lbs. Other helos (these are rough estimates) Huey about 12,000 lbs, Cobra about 14,500 lbs, Blackhawk up to 22,000 lbs, Chinook around 55,000 lbs and the Osprey is about 55,000 lbs. (Thus you can see it is not accurate to compare the V-22 to the CH-46 - the CH-47 would be a much better comparison.)