The other thing with polls like this is the interpretation factor inherent in the question itself. "Greatest" could be interpreted in so many different ways. Most powerful, most games, most quality games, best data throughput (most optimized hardware if you prefer) or even best looking, most ergonomic controller etc... etc..
All this before even taking into account that people miss out on games they may love or hate because they just didn't hear about them or couldn't find a copy or even because they hadn't been born when some of these machines came out. As long as you find enjoyment in the ones you spend your hard earned cash on that's what really matters.
