My first platinum was Call of Duty: Black Ops. Sad, yes, but hey, easy platinum if you're interested.
I've come close to getting a few other platinums but have just been extremely lazy to replay the game to get the remaining trophies. An example would be Assassin's Creed II where I experienced the trophy bug. However I'm going to return to that game today and do my best to plat it and add another to my collection.
What's the hardest Plat to get?
My first platty was Uncharted: Drake's Fortune which I imagine I share with many users
My most beloved platty is Demon's Souls (100% legit!)
The hardest platty is White Knight Chronicles (550 hours!)