Is it the original Brotherhood of Steel's drive to maintain old technologies to ensure that and mankind's progress is not lost, or is it perhaps the Enclave who dream of purging the wasteland of mutants and restoring the United States... and perhaps even the world to its former pre-war glory?
Is it the super mutants and their ambitious plan of dipping every human in a vat full of FEV? Or do you sympathize with the plight of the ghouls? Maybe the New Californian Republic and splinter Brotherhood factions in their plan to bring peace, order and justice to all corners of the United States? Or is it the raiders, and the anarchy, death and bloodshed it brings? Divulge which faction you support!
I, for one, support the Enclave. Despite their nefarious plans to wipe out the impure all around the world, and the despotic nation they will most likely create, I see them as the only real power that can actually return the world back to normal, just like it was before the war. Along with the fact that they are the pure humans, untouched by radiation and FEV, and with the most advanced technology to boot, plus the ideology that seeks to actually return the world back to normal, and finally that they are the pretty much the actual, pre-war government or at least the official descendants.
I postulate that they also have a few species from the pre-war world such as cows or seeds of plants that have not been contaminated by radiation in stasis, so the world could actually return to a pre-war state... just with fewer types of organisms I suppose.