I think this is one instance where life is much more interesting when no one really agrees! (In case it wasn't clear, my own list was more than a bit tongue in cheek, though I do think the Hansa Canon is pretty cool, and I've even gotten to handle one). But as far as what a person "should" collect, I haven't got a clue. Maybe the best sort of collectable is something which has has far more emotional appeal than monetary value.