It's funny that, almost post-for-post, the recommendations in each are identical to the vehicle in the commenter's sig!
Going back to the OP, if you intend to use it as a daily driver before doing any work, you want something as well-maintained as possible with records and receipts of the work done to it. That won't always mean the newest or the one with the fewest miles, but it's a good place to start. Timing belt replacement interval on 6G Montero engines is 60k miles, so if it's coming up on some multiple of that (120k, 180k etc) make sure that work has been done as a bare minimum. Valve guide seals are another nuisance that come up but not nearly as critical as the timing belt/water pump work.
As far as which Montero is best, all are capable rigs built like brick poophouses. A late model Gen 3 ('03-'06) will get you the newest of everything, the most powerful engine, smoothest tranny, most compliant on-road ride, etc. As you go further back in the model line-up, you lose a little bit of comfort and gain a little bit of off-road advantage. You just have to decide how much off-roadability you need and how many creature comforts you can live without (this is a very simplistic categorization and arguments can be made for each model).
As far as which ones I prefer...mine of course! Gen 2.5 fo' lyfe!