350kw? are you high? more like 270 MAX. Struggle to hit that on a stock R.
I would argue that stock for stock GTR's are much more reliable TBH. Rotors are more touchy than a woman on her period.
Basically with a rotor be ready to rebuild it. They have massive overheating issues that you need to address properly. They have the smallest heat margin i have ever seen. It's something like 10 degrees is the difference between all is well and bang. They can be trouble when trying to push too much power out of them.
In saying that GTR's have issues as well. It all depends under what application you are driving. The oil control comes into play if you want to move them in any way.
So it depends. Do you want to spend thousands fixing cooling issues in the RX7 or thousands fixing oil issues in the GTR.
Both cars will require another $5000 around that ontop of what you spend to buy it at least to make them reliable. This is not taking into account performance upgrades at all, this is the money i would spend to make them daily reliable. Provided the engines are in good condition to start with.
Also FD's are f**king tiny. No space what so ever, many people i know struggle to even fit in them. Trying to get the interior to look nice with the required gauges you need is almost impossible.
FD's do handle really nicely in stock form. You could get one and not have to touch the suspension. GTR's are not tooooo bad. In stock form they will understeer, sway bars will counter this issue.
One of my very good friends has 2001 FD3s RS currently on the boat coming here. It's going straight to Ric Shaw to get intercooler, radiator, and gauges done. He isn't even confident to drive it back to canberra without the radiator and intercooler done. They are that bad.
TL;DR they are both money pits. Don't buy 1 unless you can afford 2.
Apart from that it will be personal opinion. What one do you prefer? Do you want the braap braap of a rotor or the howl of an RB?
just my 2c.