Thought about it, and surprisingly enough I'd actually say the PS3. I owned one for about 18 months, and between it and my 360 and Wii, it was the one I played the least. That being said, I sold it to my brother right before Sony really started knocking it out of the park with their exclusives, so maybe if I'd hung onto it for a bit longer I'd have felt differently.

The original model Xbox One might also be up there, but to be honest I mainly bought it because my 360 was dying and by that point they'd added back-compatibility for all the major titles I owned, so really I got what I wanted out of the system.