For some value of 'old' perhaps.
In terms of length of official support, and aftermarket value, Apple is at the top of the game. Those strike me as the most important metrics here.
And while you might think that once official support is over, that's the end of the story, this is far from true. Those phones end up in developing markets, where there's an entire cottage industry dedicated to keeping them going. Jailbreaking is getting harder, so that might stop being an option eventually, but so far it's viable, and that's what happens.