OoT, but WW was pretty close. The enemies do little damage, the puzzles are stupidly easy, enemy patterns are easy to figure out, and they're pretty easy to dodge/block/counter. And that's for both of them.
But, you see, my first playthrough of OoT I had absolutely no trouble, even the Water Temple was stupidly easy for me. Granted on my first playthrough of OoT I didn't know about the trick to killed Gohma in five seconds, but still.
WW, however, had a couple of actually tough moments. Hitting Orca 1000 times was probably the second toughest thing I've ever done in a 3D Zelda game (the Shooting Gallery in Clock Town was a nightmare for me last time I played) and it also had a couple tough puzzles.
The Wind Temple was definately the hardest part (and it was pretty tough: a good combination of challenging puzzle solving and combat if you ask me) of the game and Molgera was a tough boss.
There was also the room in the Earth Temple that made you have to kill all the chuchus (beginning of the temple) and it took me FOREVER on my first playthrough to figure out you had to lure them into the light and then smash them with the Skull Hammer (on the bright side, I perfected the art of parrying chuchu attacks).
Also in the Earth Temple was the part where you had to burn the curtains to reveal light, get a couple purple chuchus in there and put them on the switches. That was a tough puzzle. Also, the fight with Puppet Ganon Snake Mode was savage.
I swear, I had more trouble on that boss than any other 3D Zelda boss in existance... okay, I had a lot of trouble with the bosses on my OoT Necessity Run but that was designed specifically by me to be a challenge and I wasn't doing that my first time in WW.
Anyways, I never had ANY trouble in any normal OoT playthroughs.