Here are some of the hardest trophies I got :
Dishonored - Definitive Edition : Daredevil
A lot of luck involved in this one (as most of the trophies of this DLC).
I still have a few trophies missing but I don't lose hope of getting them one day. I'm looking at you By my hand alone.
Batman Arkham Origins - Predator Parangon
As @AK-1138, I had a boosting group which ditch me and ended up doing most of the multiplayer trophies by myself including Parangon Parangon.
Very happy to got it legit even if it was a pain.
Uncharted - ...It
Unlike Batman Arkham Origins, I found very reliable players for Uncharted 4 who kept helping me even if they were done.
We managed to do it whithout the use of any glitches on the bosses.