Hmmm. I can't answer that one. Nintendo definitely has a higher quantity of popular franchises going, but of them only Zelda really interests me, and imho that series peaked on the N64 and to a lesser extent on the Nintendo handhelds.
On the other hand, I can't think of many titles developed by Sony. I know that ICO and Shadow of the Colossus were both developed by Sony, and together they were two of the most fantastic games I played on my PS2. And unlike Zelda, there aren't a hundred clones of those games. Overall I'm on the fence.