It's hard to tell which lost the most. Some figures are know but others will have been tucked away in various accounting tricks.
The Xbox and PS3 probably look the worst as the Xbox lost money and I guess you'd have to put the huge bill for R&D and getting into the console race at its feet and the PS3 looks pretty similar, with a huge chunk of R&D and selling for a big loss.
I'm not sure the 360 is out of the red yet either, as it also incurred a lot of losses initially before going profitable including the RROD $1 billion write off.
The 360 in the end I'm sure will be profitable, particularly if you attribute Live/XLBA sales to it. I think looking at current SW/HW sales the PS3 will likely be profitable in the end, too, if not massively so.
Profits wise I'd rather be Nintendo, let's put it like that.
Try to be reasonable... its easier than you think...
