I suppose that I've had as good an opportunity to compare Prado's with Disco's as anyone.
Since 2001, I've had the following (company supplied) vehicles. 1 x Prado 90 Series (diesel), 3 x Prado 120 Series (V6 petrol), 1 x Prado 120 Series (diesel) and 1 x Prado 150 Series (diesel). All of these were manual gearbox (the last three were 6 speed, the rest were 5 speed). The first four were when I was based at Kambalda - they spent most of their life on bitumen roads with only a little dirt road work and general mine site stuff (crawling over a gold heap leach operation and around the pits a bit). The last two (the diesels) were when I was based at Nullagine - and spent virtually their entire life on dirt roads, mostly pretty rough surfaces, and saw bitumen only occasionally when I went into town (Newman).
During the same period, my private vehicles were a Ford F100 (with a Chev V8 diesel in it), a Discovery 1 (V8 petrol auto), a Discovery 2 (Td5 diesel manual - which my son still owns an uses as his daily drive) and now the Discovery 4 (MY2011 2.7 litre TdV6 six speed auto).
As others have said - the Prado is not a bad vehicle. Does everything that you expect it to do, but does not really excite you. Nor does it excel in any area.
I can't really comment about the maintenance cost comparison, as the Prado's were all company maintained. On reliability though, none of these vehicles has ever let me down, other than a steering rod failure on the 90 Series Prado, and a fan belt on the same vehicle which kept it off the road for a couple of days (Goldfields Toyota did not carry a fan belt for this model in stock :o:o:o).
Of the Prado's - the 90 Series was by far the most capable off road, but still could not match the Disco 1. The 120 Series Prado was always my favourite, especially with the petrol V6 engine. On regular trips between Kalgoorlie and Perth, these vehicles did it in comfort and with plenty of "squirt" when you wanted it. But - I was glad to have a company fuel card. They are by no means an economical vehicle (about the same as the V8 Disco 1 ;)). Off road though, the 120 Series is pretty "ordinary". I remember getting stuck on a track over the heap leach at work one day that any decent 4Wd should have been able to do with ease. To prove it to the people at work (who extracted the customary "carton" from me for having to be towed out), I took the D1 out to work the next day and drove through the same spot without even needing to select low range. :D
Comfort wise, I would generally say that every model Prado falls behind the equivalent model (year / vintage) Discovery, with the exception that the 120 Series Prado is at least as comfortable as the D2 on long highway cruising. Once off road however - there is no comparison - the Disco wins hands down.
The Prado that least impressed me was the newest - the 150 Series. I would rather a good 120 Series than a 150 Series any day of the week. The newer model has become bloated. it suffers significantly in dirt road handling (the 120 Series will kill it any day) and the finish is even more cheap and nasty than previous models, with bits falling off it everywhere especially on corrugated dirt roads. I wouldn't recommend one of these to anyone. (Whoever invented that bloody horrible plastic spare wheel cover on these things needs to be shot ;)).
Probably the most noticeable area to me where the Prado simply cannot compete with the Discovery is in dust sealing, particularly around the rear tailgate door. I have yet to see a Prado where the dust does not pour in around this door when travelling on dirt roads - doesn't matter which model, they are all shockers for it.
By comparison, the Discovery 1 did leak a little bit (still not as bad as a Prado), the Discovery 2 was almost clear of dust leakage around the tailgate, and the D4 simply doesn't leak ANY dust into the cab at all - from anywhere. A little while back I was on a dirt road trip with two families in NEW Toyotas - a 200 Series Cruiser and a 150 Series Prado. When we stopped in Norseman, the women from both Toyotas were complaining about the amount of dust in the vehicles and over their luggage (and the Prado was REALLY bad) - none of them could believe how spotless the interior of my D4 was. :D
I'm not a Toyota hater .................... before the Prado's I had an 80 Series GXL Landcruiser, turbo diesel manual. This was one of the best vehicles I've ever had and would gladly have another if I could find one in good condition. But I haven't been impressed with any model Toyota since. I even test drove the new FJ Cruiser before buying the D4 as I was offered a very attractive deal on one of these through work. Now that really is a piece of crap - but it's designed for Americans, so I suppose understandable. ;)
I suppose my preference for 4WD's is pretty obvious from what I've spent my own money on ..................... after having had plenty of opportunity to compare the alternatives. ;)

