The whole point of Railroad is that they are "The Right Thing" over "The Greater Good". They are supposed to be played by those who care more about the present than the future, aka that ends do not justify the means. Players who care more about bing morally right than improving the Wasteland on the long run will choose them.
Minutemen and BoS can't be compared as BoS is much, much more than some settlement-defending militia. It is better to compare Minutemen with NCR Rangers and their ending would most likely result in Commonwealth becoming something like the NCR... or just like Yes-Man's New Vegas, a bunch of independent settlements that just mind their own business (some players would prefer NCr-like route, other would prefer a stable anarchy). Long-term, they are something between Railroad and the other two: they are more ambitious than the Railroad but not ready to fight for something even more long-term. Nice balance, but the former Minutemen were sinfully incompetent so choosing them is a risk.
It is also very interesting that you did not comment on BoS and Institute, whose entire point is that they are aiming at long-term solutions, yet focused on the ones who are more focused on short-term. If BoS wins, they conquer the Commonwealth, cleanse it of Synths, Supermutants and maybe even Ghouls and become even more powerful, thus you influence the rest of East Coast Wastelands. If institute wins, you start something new and ambitious that can go horribly right or horribly wrong... either way, something will happen and there is no more anyone that can stop the Institute's ambitions.