Well, firstly, it would need to be maneuverable, because current locations in the middle east have very tight spaces in which to put a tank.
-The tank body itself would have to be reasonably thin width wise so as to be able to fit into some of the tighter spaces of cities that dont suffer Urban Sprawl.
-It needs good armor all around, (top, bottom, left/right, front/back) to repel IEDs, RPGs, and other fire.
-The vehicle should be properly equipped to put down resistance, whether Infantry, or Armor. Easiest way (as I see it), is to take a hint from some prior vehicles, and give the tank a TOW launcher, and a anti-personnel, high-caliber weapon, such as a .50 caliber machine gun, and perhaps a MK-19 grenade launcher for long range, area suppression (such as mobs, or to deal with attackers hiding in structures deemed too important to knock down entirely or when TACAIR is not an option).
-And one of the most important functions of an APC, it should be able to quickly, and safely (safely being a relative word, since, hey, it's war) to the front lines, provide suppressing cover fire with it's weaponry, and then continue to cover their advance as needed, or to get clear so that other vehicles can deploy their teams. I'd guess that each vehicle should ideally transport between 6-10 men + weapons, armor and other battle gear semi-comfortably.