Probably "Burnout Paradise."
It was my first platinum. And I did it TWICE.
The first time for, you know, FUN. Before we had trophies.
Once Criterion Games released the trophy patch and said "they were not retro active," I figured, screw it, I'll just do it all over again.
And I had fun doing it, too.
Aside from having to fight my way to 200 PSR (which was surprisingly difficult because of the amount of scrubs who log out when losing before you are credited the points) I achieved all character specific trophies on my own since I had nobody to do it with~.