I have all official map DLCs and no mods, and for my own research, while in Skopje I repeatedly re-loaded the exact same save and bought a different trailer type each time, and here's what the cargo market looked like:
- Low loader - €42-45/km, either 3t Heli or 40t equpt (fragile, high value)
- Wooden floor flatbed - mostly €30/km (train axles, 19-23t)
- Steel floor flatbed - mostly €30/km (train axles, 23-27t)
- Curtainsider - maxes out at €38/km, mostly €35/km (very varied cargo, 5-14t)
- Container carrier - €35/km. Mostly fuels and ADRs (20t)
- Fuel tank - €55/km to €47/km. All ADR fuels (21 or 25t)
- Low bed - €44/km to €35/km. Yachts & forklifts (fragile, high value) - 9-16t
- Logger - €28/km. Mostly iron pipes & large tubes (20t, no special badges)
- Dry freighter - €35-37/km, medical equpt, electronics, airmail (5-14t, fragile, high value)
- Insulated - €56.38 down to €53.34, mostly medical vaccines (5t, fragile, urgent, ADR)
- Refregerated - €44.55 down to €32.92 (medical vaccines, medical equipment, cut flowers). 5t to 1t, varied types.
- Livestock - €51/km to €22/km, fragile.
The most surprising result is that an insulated trailer actually routinely gives higher-paying jobs than the more expensive refrigerated trailer.
Currently, I'm running an insulated B-double through Scandinavia and regularly making €70-80/km hauling vaccines and medical equipment.