I'd get an IS350. Every G series car I've ever driven has felt so unrefined. Keep wanting to love them, but they feel cheap when I test drive.
I felt the same. I used to own a 2008 G35 sedan, and even though it was labeled an Infiniti and leather everywhere, underneath it all, it still felt like a Nissan, specifically a Maxima. It wasn't very quiet, fit and finish wasn't all that great, and it wasn't smooth. It did have a great motor though. That V6 would really pull, felt more like a small V8.
My issue with Infiniti, in general, when compared to Lexus is 1) resale is not particularly good, and 2) they don't feel premium compared to a similarly equipped Nissan.
Whereas Lexus, no matter what, at least to me, never feels like Toyota.
My wife's 2008 IS250 still feels sporty yet refined to me (even though slow V6), and she still gets compliments on the car. Also, this car is really holding it's resale value.