Here's my take on those two cars
3series - I think they look great, it does look more refined. However, I hate what they've done with the back, it's become generic compared to the older signature taillight design. It's definitely more of a driver's car. Oh, by the way, most certainly you'll be labeled with the title "douchebag" or "tool" or things like that. You may not be one, but most BMW drivers are sunglasses wearing douchebags that are either dumb enough to blow their entire savings on a new BMW, or bought it with their parents' money. If you dont mind being stereotyped, get the BMW.
Gseries - I never liked them. Those things grunts everywhere. I hate Infinite/Nissan interiors, they're plastic galore. I sat in a QX56 for a Tahoe trip once, while that thing was built like a tank and it certainly felt like it could just plow through anything, I couldn't stand the interior. Anything that wasnt covered with leather was grade-A plastic. People are right when they say you WILL be bored with the car fast. The design is uninspiring inside and out. And again, those things grunts everywhere.
So if you can stand the general first impression of stepping out of a BMW, get the BMW. You'll be happier. As far as reliability goes, of course JDM wins. But still, a car should be fun.
Kind of like when I was debating on an economy car way back then. Mazda3 vs Corolla vs Civic. Sure the Corolla and Civic are more fuel efficient and can probably go 20,000miles without an oil change and still be fine. But their design was uninspiring, and they drove like... well the car just went places, that was it. Mazda3 on the other hand, it's not fuel efficient as an economy car, it's probably less reliable than the Corolla or Civic, but man is it fun to drive! (again, for an economy car). And by the way, if you really take care of your car, not much can happen to it, engines nowadays kind of take care of themselves if you dont drive it through the wall. I am closing in on 100,000miles on my 3, and I dont have a problem whatsoever, except for AC going out and getting a new one. My car still drives like the day I bought it.
Get one that will make you want to turn around and look at it one last time before you go into your house.