I'd say the list of episodes containing an effect which affects all the relevant crew, with the exception of Data are
Clues = Alien stun field
Night Terrors - Lack of REM sleep
Sarek - Negative telepathic overflow
The Perfect Mate - Alien pheromones
Genesis - Retrovirus
The Game - Addictive effects of game play
Starship Mine - Hypersonic pulse
Unnatural Selection, could be included, as he proves immune to the mutated antibody, though it only gets the chance to affect Pulaski & the station inhabitants. I think that's it. Not sure if I missed any though
Actually, I might even include Chain of Command, as Data seems to be the only one unaffected by Jellico's attitude
I can't say Cause & Effect qualifies, because he IS affected by the temporal loop just like everyone else, but they are able to use his special atributes to overcome the situation, & if we start counting those episodes too, we'll be doubling or tripling the episode count. Hell, even including his ability to tap into the Borg Collective in BoBW, was him saving the day by being more awesome than the rest of the crew
what are some other eps other than 'data's day' which are real testaments to his character?
Fistful Of Datas is one of the ones where Data is not only the one primarily affected, he literally is the affect