Ghosts N Goblins is pretty easy actually once you get the learning curve down.
My personal most difficult was Ninja Gaiden 1. That last level is insane.
Batman is up there most notably for the Joker battle which I pretty much beat with luck.
The first Turtles game is hard due to the limited continues.
Games like Battletoads I don't really count because the game was made to beat you. The only thing that keeps it from being a good game is the fact it doesn't have unlimited continues. That's inexcusable for the length of it.
I've tried some of the harder games from my childhood and been able to get through them, but Bart Vs The Space Mutants is such a failure of design, physics, playstyle and logic that it's near impossible to even want to beat, let alone try to.
Bart Vs. The Space Mutants has some of the worst controls I've ever experienced in a video game. I think run and jump used the same button. I only made it to the second level a handful of times, never got any further than that. I didn't own it though, only rented it a bunch of times. It had some cool ideas but the execution was terrible.
I'm surprised to see kid Icarus on your list. It was the second game I ever owned, after super Mario 1. It wasn't easy but I would regularly finish it. Unlike almost ever other NES game ever.
My vote goes to dragons lair. Or that f***ing "time traveller" arcade game!
Well, I beat Kid Icarus once or twice, but I'm sure you agree it's a very difficult game. I know what you mean about overcoming high difficulty: Castlevania 3 (Dracula's Curse) is definitely a tough game, but I can beat it multiple times in one sitting without too much stress, simply because I've mastered the game and gotten accustomed to its stiff controls. Same goes for Zelda 2 (The Adventure of Link), except that game doesn't have stiff controls.
Dragon's Lair does not present a fair challenge. The arcade game affords you almost no control over your character, and is arbitrary about when you can and can't control him. Bad controls (which were a byproduct of the laserdisc medium's technological limitations) artificially spiked the difficulty. As for the NES port, well, the AVGN thoroughally explained the game's faults and why its difficulty is largely a product of bad game design rather than a tough but fair challenge.
"XPW was the visual representation of ECW's corpse being molested - or, since it started before ECW ended, its body on life support being molested, like in Kill Bill." - FAN's own dynamitekid