However if we do have the cash to spend, and want something that'll really give us an edge, I suggest we build something that's as revolutionary as below:

Two man seated in hull configuration, interchangable roles of gunner and driver, with one commanding. Duplicated controls for both sides. Turret completely automated and crew observe their battlespace through sensors mounted all over the tank, optical, thermal, infrared and so on, displated on a widescreen that compresses a 360 degree arc of composited vision into 160 degrees for those on the sides. This gives them a 360 degrees awareness of the situtation and they are aware of everything, amking sneaking up on the tank impossible.
They have a main sight, and also probe sensors that extends on a stalk to allow them to see above cover and around corners without exposure. Turret top weapon is remote controled and is slaved to the crew's head movements like that of the AH-64 Apache's 30mm bushmaster chaingun.
Main weapon is prehaps a 120-140mm ETC cannon, or conventional version, depending on how technology progresses. Sensor Fuzed Munitions (smart bullets) should be able to be fired with this weapon.
Advanced powerpack should be some kind of turbine for high speed dashes, and a less fuel guzzling one for lower speed use. Hull profile, due to crewless turret, can be made low and squat.
Armor is entirely modular and should be able to be changed at any time. Should provide protection at higher levels of up to maybe even MBT rounds from the front. Active defences like ECM, smoke, thermal decoys and such, even anti-personnel WP smoke grenade launchers should be present for defence (or can even be used in offence) Linkless polymer elastic tracks that are interwoven with composite materials, making the track flexible but yet extremely tough and mine resistant (the blast causes the flexible track to twist and bend, but not fail and returning back to normal shape after blast) the tracks can also be able to take several holes without losing intergity.
Tank should also be made to be stealthy, more so then the one mentioned above.