It's rare that you can just kill someone and they've got a great weapon (I like Love/Hate, and all, but there is a big difference between the elite brass knuckles and the elite gauss rifle, which is a bad example, because that's a drop as well.) It's more likely you'll have to pick a 100 skill lock, or hack a 100 skill computer, and that lock and that computer will probably be significantly off the beaten path. One thing I will say: if you're looking for good weapons, expect to jump through a few hoops. So use what you like, and keep an eye out for weapon mods.
And some of the best weapons (the anti-materiel gun, and the fat man) don't even have special versions.
The 'special' weapons are better than the un-upgraded versions of the normal weapons, but they're not significantly better than the upgraded versions. Really though, you don't have to go through that hell. The only way to really find them all is to exhaustively search the world. The 'special' weapons are better than the un-upgraded versions of the normal weapons, but they're not significantly better than the upgraded versions.
If you play through it again, you'll find the same drops in approximately the same place.
Annabelle drops from a seemingly random nightkin). They may appear random ( LOVE/HATE for example drops from a seemingly random raider captain.
