I actually prefer length :)
Because our cervix (the entrance before you get to the uterus) is only so long so if you've got a 7 inch dick but we only only have room enough for 6 then that's an inch wasted. But our g-spot needs to be reached and we like to be filled, and a bigger girth accomplishes that.
The majority or the nerve endings in the vagina are located near the opening, so a guy with a girthy penis is able to fully stimulate this area. Length is nice for certain positions, but if it's too long it can hit your cervix.
It's the sides of the vagina that are most sensitive. Even if it's short and fat it will still be able to do the job. But long and thin really won't do anything for anyone :). Girth is definitely the winner!
Girthy penis will pleased the girls
Well I'm not a girl, but I know my fair share of biology and most of the nerve endings in a vagina are in the first few inches. Not to mention the average vagina is only about 6 inches. So anything more than an average length penis is more than is necessary... but if it's too thin then I imagine it's not going to "fill" it as much. Think of it this way. If you have a 2 inch wide hole and a 1 inch wide pole... it doesn't matter how long the pole is, it's not going to touch much of the inside of that hole.