There are so many options for tow rigs its always hard to decide.
The older chevs are good. The 6.0 deisel is a great motor. Slightly underpowered, but very reliable. The Chev IFS has the better ride of the big three, but needs a few upgrades to be reliable. Its the weakest front of the bunch.
The older 12v dodge trucks have a great motor, but in honesty I'd advoid them. The auto trans are terrible, the wiring is poor, and the body's are prone to falling apart. Its shame because the motors are so strong.
The older fords have the most durable drivetrain. Dont look at 6.5 deisle, they are grossly underpowered and hard to find parts for. The 7.3's, 94.5 and later are much better engine. The only weak part on the fords is the auto trans. The fords with the SFA's have the most durable front ends.
Given the choice I would recommend chev or ford when looking at those mid 90 years. Gas pots, or deisel.
I'd avoid something like Joey's 454 vortec unless you really like 6mpg.
If you do go with a chev, talk to joey about how to strengthen up the chev IFS front end. He just did a bunch of upgrades on his, and they are relatively cheap to do.