Oh mah holy gorsh. That's easy.
1) Spirit Tracks. All the way, man. ST is the best, always, in my (perhaps twisted)book.
2) Twilight Princess, perhaps because I spent the longest on it first play through, perhaps because I'm spending the most time these days finishing off side-quests. (But, still, you could double the hours played and I'd still have done ST for longer. The first play-through took twice as long, crazy because yes, it is a shorter game. Five files... five files that I quit on. Now seven files completed.)
3) Phantom Hourglass. I don't love it as much as ST(dang I love that game), but it's a good one. But I've only finished it twice.
4)Ocarina of time, I rarely get time to play on a console these days. But at the end of the day, at midnight o' clock, I still have my DS
5) Link's Awakening. Because I adore that game, I just don't actually own it... yeah.