The reason you're being told to not buy a Suzuki is a very good, very simple one, a couple of years ago ASMC (American Suzuki Motor company) decided to opt out of the North American market, "orphaning" their cars & trucks, although they still support their motor cycles and marine products.
Curiously enough, although GM is still around, they have not supported the Trackers to the same level as Suzuki has supported their vehicles, treating them as the proverbial "red headed step-child", and for many years folks with Trackers have been keeping them running with Suzuki parts. Yes, parts available from Autozone, RockAuto et al, and also from online sources, such as megazip.net, but like any other older, out of production vehicle, they are going to become harder to find as time goes by.
Although I am something of a Suzuki enthusiast and have no intention of parting with my 1998 second generation Grand Vitara any time soon, when my daughter who lives in Florida (I live in Guyana, South. America) if I would buy her a Suzuki in Florida, the answer was NO, and the reason is the same one that your mechanics are telling you not to buy one - part availability and finding someone to work on it.
I would say that it does not matter what year second generation you get, parts availability will not change significantly, in terms of reliability - in the US it's going to be a toss up - they didn't get the second gens until 99, by which time Suzuki had ironed out most of the early production bugs, timing chain issues are a matter of proper maintenance and can affect any or all years, 2WD drive models were available, but I can't think why you would want one. 4WD is part time, not AWD.
Historically well-built, near bulletproof, that sounds like a fitting description for a second geneartion Grand Vitara.