off-roader
Expedition Leader
The Gen II/II.5 are noticeable bigger and heavier than the Gen I Montero. The Gen II.5 is a very refined vehicle that makes for an excellent daily driver. While the Gen I looks great, it is not as trail capable, as durable or as comfortable as a Gen II/II.5. Personally I would look to get a Gen III Montero at this time. Many of the newer members are going with the Gen III Monteros and they are having great success. The Gen III is probably the best platform of the three for building an overlanding rig.
I do like the boxy look of the Gen I over all the other models. For simple overlanding, I'd choose the gen I any day.
The reality is, Overlanding isn't all that difficult for any model Montero in stock trim. If anything you may want to upgrade the tire size & possibly remove or re-enforce the stock side steps (if it came with them) but that's about all that needs to be done.
For more technical terrain (rock crawling, etc.) I'd take the mid 90's Gen II. SR trim with the locker and upgrade it appropriately as I'm doing with my 96SR.
HTH.