I have owned my sharp red 97 Monte Carlo Z34 for only four months, but it's been a great car for only paying $1200 and having 173k miles.
Doesn't get the best gas mileage, but has a lot of power and is a very reliable daily driver.
It obviously has more power than the 3.1, which is just a 2 door Lumina, and it just looks better.
I love the high-output and the dual-exhaust. The automatic shifter on the floor is great, and the alloy wheels are sweet.
The stereotype about the 3.4 being crappy is only opinion, and is because people beat up on their cars and don't keep up on regular maintenance.
I will admit it has some electrical problems, but it's 14 years old, so it's to be expected.
So far I have had to replace the water pump, and replaced the original spark plugs and wires; that combined was only $400.
My Mom has a 97 Lumina with the 3.1, and has nothing but problems, and it's very surprising that it's made it to 200k miles.
The tranny's shot, it shuts off, overheats, leaks coolant, doesn't always start etc.
To me, if you want an affordable reliable sports car that shifts and drives smoothly, you gotta go with the Z34 trim.