Wouldn't it be nice if they held "Guess the weight of this car and win it!" contests, like they do turkey?
I think the biggest question when considering the two vehicles is "What do I want in a car?"
The 6 definately has performance over the 3 (v6 at least), and it also has more room. It's also a bit more costly, but still at a very nice car for the price.
The 3 is smaller, so it weighs less, and has less power, so I think we can assume it gets better milage. It also costs less, so that is also nice. I think the 3 is an over-all well rounded car.
So if you want more performace and room, but are willing to pay a little more, I think the 6 is better. If you're looking for a nice ride, great styling, room is not too much of a concern, but cost is, then the 3 is better.
Personally, the 3 fits me better as a student, but I was also in the same situation as you, considering both. Now I'm set on the 3.