Well the reason I called it tha Alamo was for the reason you stated, barely many people lived and say what you want but the majority of us would die in the event of a zombie ridden world. And honestly even though there are many places to go there are even more flaws to them. I mean here would be some of the flaws to the places I stayed:
Mobile: you would either run out of people or resources or maybe even get killed by other survivors or goverment if they climp out of their bunkers.
Building: either you will run out of resources or you will have so many zombies around that you are over run.
Oil rig: something breaks or run out of gas, purifiers, bait ect.
Boat: crash, something breaks, someone gets sick, you run into an area without fish to eat ect.
Island: raiders find it and take over, you run out of resources, or the zombies find a way to get to it.
As you can see so many things can go wrong that it would be a small chance you would make it through the mess. That, my friends, is why I call it the Alamo, many people start off thinking they will make it when more and more enemys show up. Leading to a long and growing doom you face, however like the people that got out some may live through the nightmere of a zombie apocolypse.