I don't think the 360 won last gen, unless your just talking sales in the US alone.
The PS3 consistently outsold the 360 worldwide year on year, eventually bringing it level with 360 sales even though it was released over a year later. Not to mention the age old rumour that MS included those consoles used to replace the broken ones in RROD fiasco as sales.
The PS3 won in both sales and power, but yes, I concede it was more expensive.