Some like Contra (no cutscenes in the USA release) and Castlevania III (increased difficulty), which in my opinion the Famicom versions were far superior to the american ones.
Correct me if I am wrong, but the original NES Contra is the (U) version (although the real original is the arcade of course), the (J) version with cutscenes was released later. Therefore there was no censorship or dumbed down or whathever for american audiences. The european Probotector is of course censored.
Also although Castlevania III has overall increased difficulty over Akumajô Densetsu, Death is much
easier, for some reason.
As for the poll, of course it depends on the game. Sometimes, as in the case of Castlevania III/Akumajô Dentsetsu, it would even depend on the stage within the game.
Potentially I'd play in either English, French or German, depending on what is available. English if no decent French translation is available, French if I just want to play in my mother language, and German if I want to practice that language while having more fun than doing exercises. Since so few people use German on internet I can't practice it like I can with English, so it's why my German is so poor
In the early Nintendo days, it was common for them to forget entierely about the french speaking part of Switzerland (where I am from) and release only games with German boxes and manuals, and in rarer cases, the game itself in German language. One would probably have to go to france to buy them in french.
Playing in japanese is only an option if the ingame text does not matter, or if I know the game so well I don't need to read what is going on anymore because I already know.