So as far as figures:
The US Army has more aircraft than any one branch of military, (or USMC and Navy combined), and also has more aircraft than any other military service in the world. However, in sheer number of ROTARY WING aircraft specifically, because the Army also fields a force of fixed wing aircraft of a non-UAV nature. (even greater shocker) the Taiwan Army has the largest amount of helicopters overall, but with fixed wing, and rotary aircraft combined, the US Army has more aircraft than any other organization anywhere on the globe. Including more aircraft per ground vehicle ratio's there is no military on the planet that has as many aircraft to ground vehicles.
As far as figures go, the Army has more watercraft than any branch of the military. Combined there are more "ships" in the Army than the Navy and Coast Guard combined, ironically.
@SkrewzLoose I have thought of the Navy actually, for their Boatswans Mate MOS, but from what I"m finding, you have to be an E6 to take control of, or be assigned to an LCAC, or a Navy LCU (Navy has the same exact type of Landing Craft the Army has)
Although what I've also found looking into it, what an Electronics Technician, Operations Specialist, and Boatswans Mate would do on a Navel LCU, an Army 88K (Watercraft Operator) performs all the duties combined. Which would offer a more universal growth. As well as promotional growth to command a veseel as a Warrant Officer, Army also assigns a 68W (Medic) to every Watercraft Crew in some cases that 68W may be a 38B2W2 (or 38B2W4) depending on the mission of the landing craft, such as what I'm finding the operations that have taken places across the african coastlines, and as well as waterways in Yemen, which until this morning I had no idea the Army was conducting what are essentially river raids and other combat operations across the country, alongside the Marine Corps, and to think all we ever hear about is Afghanistan this, Afghanistan that, when we have had more than one war going on for apparently over the past decade. The Army also has medical evacuation modified landing craft as a grand collection point for wounded to be sent to for an Army Forward Surgical Team to handle before going underway. Although incredibly doubtful we will have a mass conflict that would require that, but still.
Thoughts of the Navy aren't gone, just overall, my research the past few days into the Navy aren't nearly as much as my research into the Army the past few days. Of course I'd want more of an base of education towards either branches, would rather make an informed decision over a hasty one.
One thing I've also discovered, is that in the Navy, they have Special Boat Crews as their own seperate MOS from the Boastwanes mate, while in the Army, a Watercraft Crewman, although at higher rank, from the rank of E6 and above can be assigned to an Army Special War Group, and serve on an US Army Special Boat Team under SOCOM. I'm not sure what kind of smaller craft they use compared to the SWCC, but unlike SWCC the Army speaks very, very little of them at all.
Found a blog post from 2008 from a Staff Sergeant who had gained assignment to one speaking of the support and raids with a SOF unit he left un named to wipe out training camps and wipe out what he called in his blog "High Valued Targets" but never left any names or where the attacks took place, just info on the "roar" of twin .50 cals, and chainguns vaporizing the enemy before the SOF unit he was carrying dived into the water and hit the shores, while his boat and three others dropped their teams and provided cover. What he describes was a "total wargasm" which later goes on how he pissed himself halfway through the engagement because he had not time to let it out to pee in the river. (understandably)
Other than that blog, just mentions here and there for 88Ks at the 3-level assignments, after somekind of selection program 88Ks, 88Ls, and 880A1s can get assigned to a Special Boat Team under the Army Special War Group. outside of those I cannot find anything at all about them.