Without a shadow of a doubt, Twilight Princess for me.
Maybe it's because this game is typically more story based, well this is what Nintendo actually set out to do and it showed I that the opening screen for sure. Now obviously title screen don't focus on story, I know that, but you just get sense of epicness that a true adventure awaits you. I think it's important that such an opening screen should actually set the tone for the game, let the player get a glimpse of what they're in for -- this scene does that down to a tee.
Seeing Link galloping around Hyrule field on Epona was slightly reminiscent of Ocarina of Time, which is up there with some of the best opening screens. So i guess that little piece of nostalgia was quite nice. I think it was just the backdrop behind Link and Epona though, Eldin's section of Hyrule Field was certainly the most picturesque in my opinion, it also gave you sense of the scope of the overworld itself -- setting the tone again. Then of course you have the sun setting -- typical twilight hour, which fits into the theme of the game. So all of this built up into when we see Link face to face with darkness of the Twilight Realm where he transforms into a Wolf, again this is another theme in the game.
Basically this opening screen set the tone for the game in my opinion, the setting, seeing the extent of the large world that is Hyrule, the calming music and all of this transitioning into a darker theme were Link transforms into his Wolf form. I would find myself time and time again watching this scene, in fact it just became accustom for me to do it before I got into the game, it's calm, epic and slightly dark too, just amazing.
