The R34 has the better chassis of the tree by far, but that doesn`t mean it will be so much superior because of the better chassis! It weight nealy 1700kg and the greatest achievement with the R34 GTR is that Nissan produced the best handling coupe in it`s price/size/weight class in the world. The R34 GTR is specially build to give that go-kart feeling and thanks to the stiff chassis it handles the weight so well, you think you are driving a 400kg lighter car . . . . .
Now the R32 GTR has none of this weight problems and doesn`t need such a sophisticated chassis to bounce around corners, thought the R32 GTR is 1989 welding technology, where the R34 GTR benefited from full computerized welding techniques and line robots.
As shown in this thread, uprating the front fender sections with stiffening arms on an R32 GTR is a good thing, but it isn`t a quality solution. Best is to spot weld the R32 GTR chassis, while removing previous welding spots or replacing them.
Other then the chassis issue there isn`t much that speaks for the expensive price the R34s still fetch, other then the looks. Any R32 GTR can be uprated with a Getrag mission, so this major performance gap on the R34 GTR is irrelevant, as your R32 GTR will still not cost what the bottom of the R34 GTR go for . . . . while adding a Getrag
At the end it is a personal decision about taste and cult. In europe the R34 GTR is a very big fashion machine, as it looks modern agressive and fits in to the european car culture very well . . . . in japan most GTR fans would go for an R32 GTR, as the looks issue isn`t as important over here.
The R33 GTR is also superior to the R32 GTR in many points, but it has the problem to come there with a mid 90. technology/chassis design while weighting much more then the R32 GTR . . . . the R33 GTR in my view misses the technological evolution the R34 GTR benfits from, when you speak 1500kg over sports cars.
Personaly I would choose an R32 GTR over the two others any day, then followed by an R33 GTR and some day if the used prices have droped an R34 GTR.