My first option would be PC, as long as you have good components then you will really enjoy the game. Most games are released for this format anyways and you get better graphics. Handheld devices excluding smartphones would be second.
For me:
Final Fantasy Valkyrie Profile Sim City Tales Series (most especially Tales of the Abyss) Shin Megami Tensei - Devil Summoner Series Suikoden Tactics (But the plot of stars of destiny is getting to old) Wild Arms Disgaea Knights of the Old Republic Gameshark and Codebreakers (LOL. I can't play the game without either.*i know cheating is bad, but i really want to progress in the story rather than leveling up.*)
technically speaking they are after all we can also consider phone as handheld devices. My guilty pleasure right now is candy crush as well. It's draining my phone battery so i block all incoming calls also to make sure that i aint interrupted. When i still have my PS/PS2 i normally like to play RPG genre games such the FF series.