My $.02 -
Owned several medium duty trucks - dumps, one hooklift and a flatbed.
1999 4700 DT466 with 6+1 trans - good truck, comfortable to drive but no power house, had a 14' flatbed dump The 4000 series Internationals cabs are very driver friendly.
2003 4300 DT466 with 6+1 trans - good truck, updated version of the 4700 but less reliable pertaining to the electronics in the cab and the A/C system. It had a 14' flat dump with fixed sides.
2007 Hino 268 with Hino inline 6, Aisin auto with a hooklift. This was by far and away the best medium truck I've owned. Drove from AL to SC to get the hook lift put on. It was powerful and quick, a very nice truck to drive.
2005 F650 6.7 Cummins, Allison auto with a hook lift. The worst of the bunch IMO as far as power, driveability and reliability. That truck had the issue with the fuel tanks delaminating which was a nightmare finding a Ford dealership to work on medium duty trucks under warranty.
1999 4700 DT466, 5sp with flatbed that's our current service truck. Top speed of 55 MPH loaded, unloaded, flat ground or down hill. Reliable but not much on power or speed. Currently the only medium truck we own.
I am a Ford guy from 150's to 600's but my loyalty stops at the 650. There are better options in the medium duty range out there than Ford IMHO.
The newer Allison trans are good at getting the power out of the smaller medium duty engines and easier to drive. If you are looking at the older Internationals the 6+1 gives you enough gears to get down the road at a reasonable speed. Don't buy a 466 with a 5sp - trust me.