M10 Booker. The USMC should buy 4 Tank Bns worth.

The USMC should immediately look to buying 4 Tank Bns worth. It would rebalance the GCE and make it capable of ground combat again. Its not much heavier than the ACV. Can provide shock action that Marine Infantry will need and would probably serve as a better platform for Combat Engineers (can we modify one specifically for them...like a mini ABV), could probably act as a much more stable launcher for Tomahawk missiles than rogue fires and other tasks I can't remember right now. Lastly it would be ideal for protracted ground combat in the Middle East and more probably (IMO) Africa.

The Marine Corps might want to get to its naval roots (never left it and I hate that talking point) but people live on land, not water (unless we find Atlanteans) so that is where the decisive battles will occur.

Sidenote.  One company of mobile armored recon per division ain't gonna cut it on the modern battlefield.  That might be another role for this vehicle.  If not actual recon then escort.