I would like an M1 Abrams with the 120mm smooth bore main gun.
The downside being the same as with most crew-served weapons, you really can't run one solo very well.
Abrams particularly so. Driver is all by himself (and has dismal visibility--so you need ground guides if as close as a tank-length to
anything.)
The Loader is isolated on the other side of the gun from the gunner. You don't
have to have a TC (tank commander), as the Gunner can sub (some). Gunner's field of view is pretty narrow, perhaps 10-15°, which is why you want a TC, who can have situational awareness.
Mind, the transmission takes like 100 quarts of fluid, and a fill-up is right at 500 gallons (but, you can use near any fuel). About 260 miles of road range, and about half that cross-country for that 500 gallons.
From top of my head and fuzzy memory, training ammo for the Abrams wants a 2.5km range fan. But, you get a pair of M-240s with your Abrams, and a M2 HB as well.
That Bula will be much easier to deal with.