>Actually it looks like Ebola is the one to really fear.
>Death is in days, not months or years.
Actually, this is exactly why ebola isn't the one to fear. You see, ebola kills its host far too quickly to spread really efficiently.
Ebola: You get infected in Africa, and you're dead before you even get to the next village, let alone the airport. In most cases, anyway.
HIV: You get infected in Africa, and you die a few years later, and are subclinical (i.e. not showing any signs or symptoms) for much of these years, giving you ample chance to infect everyone you come in all sorts of fun contact with.
From an evolutionary point of view, HIV is much more successful, as it has a larger reservoir of hosts.
As my virology prof explained to us, most viruses tend to attenuate with time - killing your host in particularly gruesome ways is never the parasite's goal, it's living* in the host for as long as possible and spreading to as many other hosts as possible. Therefore, it is entirely possible that in a few hundred years' time, HIV, if it weren't for medicine, would simply cease to be fatal and be more like herpes - a few cold sores every now and then, but mostly just a virus you carry around in your body without suffering any serious harm.
*Viruses aren't really alive, though that is a grey area.