Izuzu Trooper - make sure you get one with manual transmission. Automatics are problematic.
X-Terra - watch for rust and check space inside (they are small).
Tacoma - if you have money, sure. Should be dependable and will keep good resell value. Just check the frame for rust.
Old Rangers - first gen? Looks cool but some parts are hard to come by these days. I think i.e. fuel tank is impossible to get.
Frontiers - Should be decent and can be found newer than Tooper or X-Terra and cheaper than Tacoma.
Parts for Rangers are more available than most, fuel tanks vary because they changed over the years, EFI ones are pretty available. Different wheelbases obviously have different tanks too. I suspect most trucks of that vintage will be similar.
For a noob owner, I would recommend 90-97. They have EFI, they have the better trans, they have better axles etc. It all bolts onto the older trucks (I did it to mine) but turnkey out of the box the second and third gen has it all (4.0)
They are like an erector set, I have had a lot of fun with mine.
Accept the fact that they are basically a two seater (any truck of comparable size standard or extended cab)
Ease of working on... simplicity kind of plays a factor. My V8 swapped Ranger is generally easier to work on than any fullsize I have had to date. Maybe it is because I more or less designed it myself but still...
Depending on options even old compacts can have similar ratings to average half tons, my '85 has a longer bed than my LWB F-150 also so there is that. With new bushings, good springs, new shocks and good tires it is perfectly fine on the highway, not as smooth as my wife's new Bronco offroad but then again my suspension actually articulates...
Huge beyond huge thing though, no matter what you get realize you are buying a 30yo truck. It will need some love because the level of care you have to maintain for reliable overlanding/offroading is likely not the same level of care it has been getting for the last 25 years. Brakes, brake hoses, wheel bearings/seals, u-joints, suspension joints, cab mounts, belts, alternator/charging system etc. Also you are getting out of the envelope most shops are familiar with so strong DIY skills go a long ways too.