Out of the 3, I would say Platinum. Actually I've only gotten a used copy of it recently and I'm still playing the last person's file but still so far I've noticed it runs smoother and faster than DP did. Diamond and Pearl are pretty slow moving and Platinum fixes these problems up. Plus I love the aesthetic changes added to the game. The snow on the ground, the gates at the entrances in Floaroma Town, the remodeled look of Amity Square , the new battle menu, the redesigns of Eterna, Veilstone , and Hearthrome , the games look visually better. I also like how some trainers now use Seals. Everything about the games are a total step forward from Diamond and Pearl.