Not sure what you are looking for exactly. I've never driven an Rb20, Rb25 or Rb26 powered car.
I have driven:
L24
L26
L28
L28 Turbo
L28 EFI
L31 Stroker
SR20
RB30 ET
The L24 is a punchy motor, in fact I much prefer the feel of early 240z over early 260z's with the original emission controlled carbs. The L24 revs very nicely when in good tune, but power like all L-series engines starts to drop after 5,500rpm
L26 (stock) is ok, but a little bland compared to stock L24.
l28 (stock) depends on which car its in, but its less willing to rev, but feels more torquey. EFI set up is very smooth but saps some top end power (depends on the year and intake manifold efi setup etc..).
L28 turbo was a carby turbo set up. It was pinging at the time so I didn't flog it hard. Not really a great experience, could be made to go fast but sounded like a vacuum cleaner. Fuel hungry.
L31 Stroker - Great engine loved it. Very strong and very torquey. This engine had been modified and balanced / hence loved to rev had plenty of steam, but limited at top end by SU carbs. Triples would be fantastic. (Hence reason I'm building one).
SR20 is a great little engine, if I didn't buy a Z, I would have got a Silvia S15 or a 180sx. Great cars and the SR20 feels really responsive and has good torque for a 4 banger. Good on fuel too.
Rb30 ET - Drove it in a VL chommodore . It was mated to an auto so not the best, was a fast car but I hate VL's and I hate auto's. Plenty of low down torque, fuel hungry and lots of crazy turbo noises from the wastegate. A good engine (wouldn't want an auto one in a Z though) and not as rev friendly as the L-series.
I think a perfect combo is the RB30 block with the 25 / 26 head if your into that kind of thing. However I tend to like smaller engines that rev really hard too and in a sports car like a Z its quite nice to be able to rev it up quickly and freely.
I really like the feel of the old L24 in a 240z. Something about it, its like Nissan got it just right. Then emission rules ruined everything. As a daily driver a L24 in a 240z is not too fuel hungry and seems to be pretty good. In fact many studies have failed to prove that all that emission gear they added in the 70's to carby does actually did any good. In some cases some people think that it makes their cars more fuel hungry and they get worse fuel enconomy.
Remember most of these cars are probably going to lack regular maintenance and as a result may not drive like you want them to.
a well maintained early 240z on hitachi carbs with correct ignition timing and engine is a true joy to drive. However a fuel injected later RB engine in a Z might be just the ticket you need in a daily driver.