STOP. BEING. DUMB. Sony HAS NEVER and WILL NEVER develop a 1st party title. SONY IS NOT A DEVELOPER. They are a publisher. The only exclusives they have are at best 2nd party titles (i.e. GT4, God of War, Ico/SotC, etc.) and at worst 3rd party exclusives (i.e. Virtua Fighter, Final Fantasy, etc. which are getting more and more rare).
Sadly enough, if we were to get into a "best developer" debate, I'd probably be tempted to go with Namco/Bandai. Nintendo is the best 1st-party developer, since I believe it is also the ONLY 1st-party developer now that Sega is software-only.
EDIT: Forgive me, I lied. Apparently SCE developed Ape Escape and LocoRoco.
EDIT 2: It seems the only difference between Sony and Nintendo is that Sony incorporates their 2nd-party devs to make them look like 1st-party. Nintendo keeps themselves separate as a developer from their 2nd-party devs.
EDIT 3: What the heck. Apparently I don't know anything, and you should ignore this whole post. Somehow Intelligent Design and Retro Studios are 1st-party...