several reasons
What made me consider the G6? I think I saw some at carmax or autotrader and they caught my eye. I was looking for an American car, under 12K, with at least a V6. I looked good and hard at Fusions but after I saw a G6 in person at the carmax lot it just stuck in my head. The exterior caught my eye and i had to take a look inside. I fell in love with the sporty interior looks at first sight too. The ones they had a carmax were expensive though and several K above my budget (carmax is good, I suppose, but undoubtedly expensive).
I found the G6 I ended up with on Autotrader near by. I went to go look at it and test drive it and I was hooked on it. The car started up so smoothly that I had to sit for a second and listen to see if it actually had started. The cool red needles shifted from right to left and back and it all amazed me. The color (electric metallic blue) was probably the one thing that made me and my wife most hesitant about getting the car. However, I've come to love it since it's not a cookie-cutter car color but my wife is still iffy about it.
Anyway, it was under 12K and had a superior amount of features when compared to any other car in its price range: V6, upgraded sound system, sunroof, 17" wheels, CD player and upgraded sound system, remote start, and telescoping steering wheel. Along with this the GM CPO warranty and relatively low mileage on the car. The GM CPO woops the carmax warranty and the car was a lot cheaper than any of the G6s at carmax too.
Overall, the G6 GT was a perfect balance in price, power, looks, and features for me.