My opinion is going to be jaded, because the only one of these cars I've driven has been the G35.
I also have only driven the coupe, as the sedan that was parked next to it on the lot felt a bit tight about my shoulders. But if the performance compares, The G35 is the car for me.
IVe had too many GM cars to fully trust one. Hell, I currently own 3 Chevies, and Have had 2 Pontiacs, another Chev, and an Olds, that have ranged from the "basic" (Chevy/Geo Metro) to "fairly well optioned" (Pontiac 6000 LE). I only really "trust" the Metro. Very simple car with few options, and fewer things to break.
As most GM cars are built out of the same parts, I'm only impressed with the fact that if you buy a 'Vette, or one of Caddie's fancy models, you can find a GM dealer (or 3) near most every town in the United States for service.
I've had one Toyota, and while it is very reliable, repairs and upkeep "feel" very much like I'm spending "Sports Car" money on a damn Camry. Not long ago, new rear suspension components and 2 stock all weather tires cost me nearly $1,000.
The Camry is also very hard on Front disc brakes. I've yet to replace the pads and been able to have the rotors "turned." My brake pads in front are usually good for about 20K miles, and I have historically had to replace the rotors when I replace the pads, and I'm coming up on time to do it again.
I've had one other Nissan car, and it was designed to be one the world's "throw-away" basic transportation cars. (Early Sentra)
But even so, it was damn near bullet-proof. Hell, If I was able to maintain it the way I'm able to maintain the current fleet, I might still be driving it. (It survived 2 Years as a Pizza delivery vehicle near the end of it's time with me.) I did not in any way baby that little car, and in 10 years or more of owning it I replaced a clutch, timing belt, and head gasket. Every thing else included it's "regular" 10-15,000 mile oil change, and a once a year wash so I could see out the windows.
Now Nissans are even tougher...
The choice would be easy for me. G35. Especially seeing as a similarly equipped Maxima is about the same amount of money.