I bred my own pure sativa strain from Durban Poison, Swazi and another sativa I can't remember the name of and the girls from the seed absolutely produced big fat, dense buds. The girls, outdoors, grew to about 10 foot tall, had trunks the size of your wrist and threw 2 pounds minimum dry weight per plant.
I can't grow this strain in my grow room cos it's not big enough.
But, my point is, you can get massive buds off a sativa. They're not always long and thin.
My strain, and the original Durban Poison mother it was based on, used to get dense buds a foot long and thicker than a beer can. The fuckers needed stakes to keep the branches from snapping.