Probably the Xbox 360. My parents bought me one back on 2006 without me even asking for it (and we weren't doing too hot financially, so it was just a pleasant surprise), and I ended up loving it. Too many memories, frustration, nostalgia and fun poured into a single console, nothing can really beat it. It also brings me back to times where things where much simpler and more enjoyable altogether, at least on a personal level.
Plus, my closest friends bought a PS3, so we started doing what we called "cultural exchanges" from time to time, where we would lend each other's consoles and play through the respective console's exclusives. It spiced things up from time to time, and prevented a full "only-one" console fatigue, thus making it more especial whenever it came back home.
